Most repeated PTE questions, by task, with answers.

Archaeologists studying the ancient city uncovered a network of underground channels that once carried fresh water to thousands of households. The sophistication of this system suggests that the inhabitants possessed advanced engineering knowledge. By analysing sediment trapped within the pipes, researchers were able to estimate how the population grew and eventually declined over several centuries of continuous settlement.

Economists have long observed that consumers rarely behave as perfectly rational decision makers. When faced with too many options, shoppers often delay their choices or abandon a purchase entirely. This tendency, known as choice overload, has prompted some retailers to simplify their product ranges, reasoning that a smaller, clearer selection encourages customers to buy with greater confidence.

Astronomers using powerful telescopes have identified distant planets orbiting stars far beyond our solar system. By measuring the slight dimming of starlight as a planet passes in front of its star, scientists can estimate the planet's size and the length of its orbit. Some of these worlds lie within a region where liquid water, and perhaps life, might exist.

Children acquire language with remarkable speed during their earliest years, absorbing grammar and vocabulary long before they receive any formal instruction. Researchers believe this rapid learning depends on constant exposure to conversation rather than deliberate teaching. By listening to those around them, infants gradually detect patterns, test their own attempts, and refine their speech until it resembles that of fluent adult speakers.

The development of vaccines ranks among the most significant achievements in the history of medicine. By training the immune system to recognise a harmful organism in advance, vaccination prevents illness before it can take hold. Widespread immunisation programmes have dramatically reduced diseases that once claimed millions of lives, demonstrating how scientific cooperation across nations can protect entire populations from infection.

Rivers have shaped human civilisation for thousands of years, providing water for agriculture, routes for transport, and fertile soil for growing crops. Many of the world's earliest cities developed along their banks, where reliable flooding renewed the land each season. Today, however, growing demand and changing rainfall patterns place increasing pressure on these vital and often shared waterways.

Chart: Journeys per person per year, Great Britain

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Chart: Renewable share of electricity, 2010–2022

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Chart: Average monthly household budget

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Chart: Life expectancy at birth by country and sex

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Chart: International student enrolment by host country

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Chart: Urban versus rural population share

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Today I want to talk about how cities are turning their rooftops into gardens. The basic idea is simple: empty roof space can grow plants, and that brings several clear benefits. First, the plants absorb rainwater, so during heavy storms less water rushes into the drains all at once. This reduces the risk of flooding in the streets below. Second, a layer of soil and greenery keeps the building cooler in summer, which means residents rely less on air conditioning and use less energy. Third, these green roofs give bees, butterflies and birds a place to feed and rest, even in the middle of a busy city. Now, there are challenges. Roofs must be strong enough to carry the extra weight of wet soil, and someone has to water and maintain the plants. But many planners argue the long-term gains for the climate and for residents are well worth that initial effort and cost.

I'd like to introduce you to a remarkable woman named Mary Anning, who lived on the south coast of England in the early eighteen hundreds. As a child, she collected fossils from the cliffs near her home and sold them to support her poor family. But Anning was far more than a collector. At just twelve years old, she helped uncover the first complete skeleton of an ichthyosaur, a giant marine reptile. Later she discovered other extraordinary creatures, including long-necked plesiosaurs. Her careful work gave scientists vital evidence that whole species had once existed and then vanished from the Earth. Yet because she was a woman, and from a working-class background, the gentlemen scholars of her day rarely credited her by name in their published papers. It was only many years after her death that her enormous contribution to the science of palaeontology was properly recognised and celebrated.

Let's look at why a good night's sleep does so much more than simply make us feel rested. While we sleep, the brain is surprisingly busy. During the deeper stages, it appears to sort through the day's experiences, strengthening the connections that store important memories and weakening those it no longer needs. This is one reason students who sleep well after studying tend to remember more the next day. Sleep also seems to act like a cleaning system for the brain, clearing away certain waste products that build up while we are awake. On top of that, the body uses this time to repair tissue and to support the immune system, which helps us fight off illness. So when people regularly cut their sleep short, they may notice poorer memory, weaker concentration and more frequent colds. The clear message from researchers is that sleep is not wasted time, but essential maintenance for both body and mind.

Today I want to compare two very different ways that animals survive the cold of winter. The first strategy is migration. Many birds, for example, simply leave. As temperatures drop and food becomes scarce, they fly thousands of kilometres to warmer regions, then return when spring arrives. This demands enormous energy, but it lets them avoid the harshest conditions altogether. The second strategy is hibernation. Instead of travelling, animals such as certain ground squirrels stay put and dramatically slow their bodies down. Their heart rate falls, their body temperature drops close to freezing, and they live off fat reserves stored during autumn. In effect, they sleep through the season. Both approaches solve the same basic problem of scarce winter food, but in opposite ways: one by escaping the cold, the other by enduring it in a state of deep rest. Which strategy an animal uses depends largely on its size, diet and habitat.

I'd like to discuss a clever solution to a growing problem in our oceans: plastic waste. Every year, huge amounts of plastic end up in the sea, where it breaks into tiny fragments that harm fish and seabirds. One promising response comes from the world of design. Engineers have begun creating floating barriers that drift with the ocean currents, gathering plastic into a central point where it can be collected by boats and taken ashore for recycling. The idea is to let the ocean's own movement do much of the work, rather than relying on costly fuel-hungry vessels to chase the rubbish. Early trials have had mixed results, since storms can damage the equipment and very small particles still slip through. Still, supporters argue that combining this clean-up technology with efforts to stop plastic entering the sea in the first place offers our best hope of protecting marine life for future generations.

Let's explore the surprising science of how colour affects the way we behave. Researchers have found that the colours around us can influence our mood, our choices and even our sense of time. Take restaurants, for example. Warm colours like red and orange are thought to stimulate appetite and create a lively atmosphere, which is why many fast-food chains favour them. Hospitals and clinics, on the other hand, often choose soft blues and greens, because these shades tend to feel calm and reassuring to anxious patients. Colour can also affect how hard a space feels to wait in: studies suggest that time seems to pass more slowly in rooms painted in cool tones. Of course, our reactions are not identical, and culture shapes them too, since a colour seen as joyful in one society may signal mourning in another. The key lesson is that colour is never simply decoration; it quietly guides how we feel and act.

Moderator: Today we're discussing whether cities should make public transport completely free of charge. Speaker one, what's your view? Speaker one: I strongly support it. Free buses and trains would cut car use, reduce pollution, and help low-income residents who struggle with rising fares every month. Speaker two: I understand that, but transport systems still cost money to run. If fares disappear, the bill falls on taxpayers, and services might decline without that steady income. Speaker one: Cities could fund it through parking charges and fuel taxes, so drivers who cause congestion pay their share instead of ordinary commuters. Speaker two: Perhaps, yet evidence from trial cities is mixed. Some saw crowding rise sharply while overall car traffic barely changed at all.

Moderator: Our panel is debating whether universities should drop traditional exams in favour of continuous assessment. Speaker one? Speaker one: Continuous assessment is fairer. It measures steady effort across the term rather than how a student performs during three stressful hours that may not reflect real ability. Speaker two: I disagree. Final exams test whether knowledge has truly been retained and understood, and they are much harder for students to cheat their way through. Speaker one: But constant coursework reduces anxiety and rewards consistent learning, which actually matches how people work in most professional jobs later in life. Speaker two: Yet coursework can overload students with deadlines, and busy markers may struggle to grade so many separate tasks consistently and reliably.

Moderator: Let's consider whether companies should permanently allow employees to work from home. Speaker one, please begin. Speaker one: Remote work boosts productivity and saves hours of commuting. Staff report better balance, and firms can hire talented people regardless of where they happen to live. Speaker two: That sounds appealing, but offices build culture. Spontaneous conversations spark ideas, and new employees learn far more quickly when experienced colleagues sit beside them. Speaker one: Video tools handle collaboration well now, and reduced office space cuts company costs while shrinking the daily carbon footprint of thousands of commuters. Speaker two: Even so, isolation harms wellbeing for some workers, and managers find it harder to support struggling team members they rarely meet face to face.

Moderator: Today's question is whether governments should heavily tax sugary drinks to improve public health. Speaker one? Speaker one: Yes, a sugar tax works. It pushes manufacturers to lower sugar levels and discourages buying, which over time reduces obesity and dental problems among children. Speaker two: I'm not convinced. Such taxes hit poorer families hardest, since they spend a larger share of income on everyday food and drink. Speaker one: But the revenue can fund school sports and clinics, and several countries have already seen drink makers quietly reformulate their recipes. Speaker two: People may simply switch to other unhealthy snacks instead, so the tax treats one symptom while ignoring the wider causes of poor diet.

Moderator: Our topic is whether children should be given smartphones before they reach secondary school. Speaker one, your thoughts? Speaker one: I think early access helps. Phones let parents stay in touch, teach digital skills young, and allow kids to look up information for schoolwork. Speaker two: I'd be cautious. Young children can become addicted to screens, lose sleep, and stumble onto harmful content before they can judge it sensibly. Speaker one: Parental controls and screen-time limits manage those risks, and avoiding technology entirely just leaves children behind their peers. Speaker two: Filters are imperfect, though, and constant notifications shorten attention spans, which can quietly damage concentration and early learning habits.

Moderator: Let's debate whether tourists should pay higher fees to visit fragile natural sites. Speaker one, please start. Speaker one: Higher fees make sense. They limit crowds that damage trails and wildlife, and the money funds rangers, repairs, and conservation projects. Speaker two: I see problems, though. Steep charges turn natural wonders into experiences only wealthy travellers can afford, which feels deeply unfair. Speaker one: Locals and students could receive discounts, so the policy targets mass tourism rather than ordinary curious visitors. Speaker two: Even then, communities that rely on tourist spending might lose vital income if visitor numbers fall too sharply across the year.

You ordered a laptop online, but the package that arrived contains a different model. You call the store. What would you say to the customer service agent?

Your downstairs neighbour plays loud music late at night, and it keeps you awake before work. You decide to speak to them. What would you say?

You missed an important class because you were unwell, and now you need the notes. You approach your professor after the next lecture. What would you say?

A friend invites you to a weekend trip, but you have already promised to help your family that day. What would you say to your friend?

You bought a coffee machine two weeks ago, and it has already stopped working. You return to the shop. What would you say to the assistant?

You are new to the city and cannot find the train station. You stop a passer-by on the street. What would you say?

The development of standardized shipping containers in the 1950s quietly transformed the global economy more than almost any other postwar innovation. Before containerization, goods were loaded onto ships piece by piece, a slow and expensive process that left cargo exposed to theft and damage. An American trucking entrepreneur named Malcolm McLean reasoned that loading entire sealed boxes, rather than individual items, would dramatically cut both time and cost. His insight proved correct on a scale few anticipated. A container that once took days to load could now be transferred between ship, train, and lorry in minutes, because every vehicle was redesigned around the same dimensions. The economic consequences rippled outward steadily. Ports that adopted the system flourished, while older harbours unable to handle the heavy cranes and wide storage yards gradually declined. Shipping costs fell so sharply that manufacturers could locate factories thousands of kilometres from their customers and still compete on price. This made it economical to assemble a single product from parts sourced across several continents, laying the groundwork for the complex supply chains that define modern commerce. Critics note that the same efficiency hollowed out manufacturing in wealthy nations, as production migrated toward regions with cheaper labour. Workers in traditional dockside communities lost employment, and entire neighbourhoods that depended on the old labour-intensive ports faded. Yet the container also lowered the price of countless consumer goods, putting clothing, electronics, and household items within reach of ordinary families. The unremarkable steel box, rarely noticed by the public, thus reshaped where things are made, how they travel, and ultimately what they cost everyone.

For most of the twentieth century, scientists assumed that the adult human brain was essentially fixed, its structure set early in life and incapable of meaningful change thereafter. This view shaped medicine and education alike, encouraging the belief that recovery from brain injury was largely impossible and that learning slowed inevitably with age. Research over the past few decades has overturned this assumption decisively. The brain, it turns out, remains remarkably plastic, continually reorganizing its connections in response to experience, practice, and even injury. When one region is damaged, neighbouring areas can sometimes take over its functions, a phenomenon that explains why some stroke patients regain abilities once thought permanently lost. This capacity, known as neuroplasticity, depends heavily on repeated activity; connections that are used frequently are strengthened, while those left idle gradually weaken. The implications extend well beyond the clinic. Musicians who practise an instrument for years show measurable enlargement in the brain regions governing finger control and hearing. Taxi drivers who memorize sprawling street networks develop a denser region associated with spatial memory. Such findings suggest that the brain physically adapts to the demands placed upon it, much as a muscle responds to exercise. However, plasticity is not always beneficial. The same mechanism that supports recovery can entrench harmful patterns, reinforcing chronic pain or addiction when those circuits are repeatedly activated. Researchers therefore caution that the brain's flexibility is a double-edged tool rather than a simple gift. Understanding how to direct this adaptability, encouraging useful changes while discouraging destructive ones, has become one of the central challenges of modern neuroscience and a promising frontier for treating disorders once considered hopeless.

The eruption of the Indonesian volcano Tambora in 1815 was the most powerful in recorded history, yet its most dramatic effects were felt thousands of kilometres away, the following year. The explosion hurled enormous quantities of ash and sulphur dioxide high into the atmosphere, where the gas reacted to form a fine veil of particles that spread across the globe. This veil reflected sunlight back into space, lowering temperatures worldwide and producing what contemporaries called 'the year without a summer'. In Europe and North America, frosts struck in June and July, ruining harvests that should have ripened in warmth. Crops failed across wide regions, and the resulting food shortages drove prices to extraordinary heights. Hunger spread quickly, and with it came disease and social unrest, as desperate populations searched for grain that simply did not exist. The disruption reached unexpected corners of human life. The shortage of oats left many unable to feed their horses, which prompted a German inventor to design an early two-wheeled vehicle propelled by the rider's feet, an ancestor of the modern bicycle. Cold, gloomy weather kept a group of writers indoors near a Swiss lake, where a ghost-story competition inspired one of them to begin a novel that became a landmark of horror fiction. Even artists noticed the change, painting unusually vivid sunsets coloured by the lingering atmospheric dust. The episode stands as a striking reminder that a single geological event, occurring in one remote location, can ripple across continents to disturb agriculture, economies, and even the course of culture in ways no one at the time could have predicted or understood.

Few crops have shaped a continent as profoundly as the potato shaped Europe. Originally domesticated in the Andes mountains of South America thousands of years ago, the potato was carried back to Europe by Spanish ships in the sixteenth century, where it was at first regarded with deep suspicion. Many believed the strange tuber was poisonous or unfit for human consumption, and for decades it was grown mainly to feed animals or as a curiosity in botanical gardens. Gradually, however, its remarkable advantages became impossible to ignore. The potato produced far more calories per acre than grain, grew well in poor soil, and could be left in the ground until needed, making it a reliable defence against famine. As governments encouraged its cultivation, populations across northern Europe expanded rapidly, fuelled by this cheap and dependable source of nutrition. Some historians argue that the potato indirectly enabled the continent's later industrial growth by feeding the workers who crowded into expanding cities. Yet this very dependence carried hidden dangers. In regions where people relied on a single variety of potato for nearly all their food, the crop's failure could be catastrophic. When a fungal disease swept across Ireland in the 1840s, the potato harvest collapsed almost entirely, and the resulting famine killed roughly a million people while driving many more to emigrate overseas. The disaster demonstrated, at terrible cost, the fragility of any society that stakes its survival on one crop. The potato's history thus contains a double lesson: a humble plant can lift millions out of hunger, yet overreliance on it can leave those same millions dangerously exposed to ruin.

Beneath the forest floor lies a hidden network that scientists have only recently begun to appreciate. Trees, long imagined as solitary individuals competing for light and water, are in fact connected to one another through vast underground partnerships with fungi. The thread-like filaments of these fungi wrap around and penetrate tree roots, forming a relationship from which both partners benefit. The fungi absorb water and essential minerals from the soil and pass them to the tree, while the tree supplies the fungi with sugars produced through its leaves. What has surprised researchers most is the scale and sophistication of this system. The fungal threads of neighbouring trees often join together, creating an interconnected web that links many individuals across a forest. Through these connections, trees appear able to share resources, sending carbon and nutrients to seedlings struggling in the shade or to neighbours weakened by drought. Some experiments suggest that older, larger trees act as hubs, channelling support to younger ones and even recognizing their own offspring. There is also evidence that trees use the network to transmit chemical warnings; when one tree is attacked by insects, others nearby may receive signals that prompt them to strengthen their defences. These discoveries challenge the long-standing image of the forest as a battlefield of ruthless competition. Instead, they reveal a community in which cooperation, communication, and mutual dependence play central roles alongside competition. Understanding this network has practical importance, too. It suggests that protecting forests means preserving not only the visible trees but also the invisible fungal partnerships beneath them, without which the entire system might function far less effectively than it currently does.

When the Eiffel Tower was completed in 1889 for the Paris World's Fair, it was widely regarded as an eyesore that disgraced the elegant skyline of the French capital. A group of prominent artists and writers published an angry protest denouncing the iron structure as useless, monstrous, and an insult to French taste. The tower was, in fact, intended as a temporary exhibit, scheduled to be dismantled after twenty years once its permit expired. Its designer, the engineer Gustave Eiffel, understood that public opinion alone might not save his creation, so he searched for a practical justification to keep it standing. The answer lay in the emerging science of radio. Eiffel offered the summit of the tower as a platform for antennas, recognizing that its great height made it ideal for transmitting and receiving signals over long distances. The military soon found these capabilities invaluable, using the tower to intercept enemy communications during the First World War. This scientific usefulness gave authorities a compelling reason to preserve the structure long after its original permit would have expired. Over the following decades, attitudes shifted dramatically. The very features once mocked as ugly came to be celebrated as bold and modern, and the tower gradually transformed into the beloved symbol of Paris recognized around the world today. Its story illustrates how the fate of a monument can depend less on beauty than on usefulness, and how public taste can reverse itself entirely within a generation. What began as a despised temporary curiosity survived precisely because it proved practically valuable, and only later did it earn the affection that now seems to have been inevitable from the start.

Some people believe that remote work makes employees more productive, while others argue it weakens teamwork. Discuss both views and give your own opinion.

Many cities are introducing congestion charges to reduce traffic in their centres. What are the advantages and disadvantages of this policy?

Some people think governments should fund space exploration, while others believe the money should solve problems on Earth. To what extent do you agree or disagree?

In many countries, the proportion of older people is increasing rapidly. Do the advantages of an ageing population outweigh the disadvantages?

Some argue that university education should be free for all citizens, while others believe students should pay tuition fees. Discuss both views and give your opinion.

The rise of online shopping has changed how people buy goods. Do you think this trend has a positive or negative effect on traditional high-street stores?

The development of standardised shipping containers in the 1950s reduced the cost of transporting goods across oceans. Before this innovation, dockworkers loaded cargo by hand, a process that was both slow and expensive. The metal boxes could be stacked, sealed, and moved directly onto trucks or trains. As a result, global trade expanded rapidly and reshaped the world economy within a few decades.

Sleep plays a vital role in how the brain stores new memories. During deep sleep, the connections formed while learning are strengthened and transferred into long-term storage. Studies show that students who sleep well after studying tend to recall information more accurately than those who stay awake. Researchers therefore argue that regular rest is as important to learning as the study itself.

Coffee was first cultivated in the highlands of Ethiopia before spreading across the Arabian Peninsula. Traders carried the beans to ports where merchants recognised their value for both flavour and energy. By the seventeenth century, coffee houses had emerged throughout Europe, becoming lively centres of conversation and debate. Some governments even tried to ban these gatherings, fearing that they encouraged political unrest.

Volcanic eruptions can have a surprising impact on the global climate. When a large volcano erupts, it releases ash and gases that rise high into the atmosphere. These particles reflect sunlight back into space, causing temperatures at the surface to fall for months. Although the effect is temporary, historical records show that major eruptions have occasionally led to poor harvests and widespread hardship in distant regions.

The invention of the bicycle in the nineteenth century gave ordinary people a new sense of freedom. For the first time, individuals could travel several miles without depending on horses or public transport. This freedom was especially significant for women, who gained greater independence in their daily lives. Some historians suggest that the bicycle quietly contributed to wider social change across Europe and North America.

Bees are essential to agriculture because they pollinate the flowers of many food crops. As a bee moves from plant to plant collecting nectar, pollen sticks to its body and is carried to the next flower. Without this service, the yields of fruits and vegetables would fall sharply. For this reason, scientists are deeply concerned about recent declines in bee populations around the world.

The Sahara has not always been a desert. Geological and fossil evidence shows that, between roughly eleven and five thousand years ago, much of North Africa was a green landscape of lakes, grassland and rivers. Rock paintings from the period depict cattle, hippos and human swimmers, scenes impossible in today's arid climate. Scientists attribute this 'Green Sahara' to small, cyclical changes in the tilt of the Earth's axis, which strengthened the seasonal monsoon and drew rainfall far inland. As the planet's orientation gradually shifted again, the rains retreated, vegetation died back, and within a few centuries the region returned to the desert we recognise. Researchers note that this drying was not perfectly steady; it appears to have happened in uneven pulses rather than a single smooth decline.

According to the passage, which of the following are true of the 'Green Sahara'?

• ✓Changes in the tilt of the Earth's axis strengthened the monsoon
• ·The region was permanently transformed and never reverted to desert
• ✓Rock paintings from the period show animals such as cattle and hippos
• ✓The eventual drying happened in uneven pulses rather than smoothly
• ·Human settlement of the area was impossible during this time

The placebo effect describes a genuine improvement in a patient's condition after receiving a treatment with no active ingredient, such as a sugar pill. Far from being imaginary, the response can be measured: brain imaging shows the release of natural painkillers, and some patients report real relief from symptoms. The effect appears stronger when the patient expects to improve, when the ritual of treatment feels convincing, and when a trusted clinician delivers it. Researchers stress, however, that placebos do not shrink tumours or cure infections; their influence is largely confined to symptoms shaped by the brain, such as pain, nausea and fatigue. Understanding the effect is vital for clinical trials, where new drugs must outperform a placebo to be judged genuinely effective.

According to the passage, which statements about the placebo effect are supported?

• ✓It tends to be stronger when the patient expects to improve
• ·It is effective at curing infections and shrinking tumours
• ✓It can produce measurable changes such as the release of natural painkillers
• ·It is purely imaginary and produces no real relief
• ✓New drugs in trials must outperform it to be judged effective

Microfinance, the practice of lending very small sums to people excluded from ordinary banks, was once hailed as a near-magical cure for poverty. Pioneered in South Asia, it allowed borrowers, many of them women, to buy a sewing machine or a few goats and start a modest business. Supporters argued that even tiny loans could unlock self-reliance and dignity. More cautious studies have since tempered the early enthusiasm. They find that microloans rarely lift whole communities out of poverty and can leave vulnerable borrowers trapped by high interest rates if a venture fails. Yet the same research suggests genuine benefits: households often gain a smoother income, greater control over spending, and improved bargaining power within the family. The current consensus treats microfinance as a useful tool rather than a cure-all.

According to the passage, which of the following are true of microfinance?

• ✓High interest rates can trap vulnerable borrowers if a venture fails
• ✓It can give households a smoother income and greater control over spending
• ✓It involves lending very small sums to people excluded from ordinary banks
• ·Experts now regard it as a guaranteed cure for poverty
• ·Careful studies show it reliably lifts whole communities out of poverty

The Antikythera mechanism is among the most astonishing objects to survive from the ancient world. Recovered in 1901 from a Roman-era shipwreck off a Greek island, the corroded bronze device dates to roughly the second century BCE. Inside its remains, researchers using X-ray imaging have found dozens of finely cut gears, arranged to model the movements of the Sun, Moon and known planets. By turning a handle, an ancient user could predict the positions of celestial bodies and even forecast eclipses. Nothing of comparable mechanical complexity is known again for well over a thousand years. Historians debate who built it and how the knowledge was lost, but the mechanism overturns the old assumption that such sophisticated gearing was beyond the reach of the ancient Greeks.

According to the passage, which of the following are true of the Antikythera mechanism?

• ✓It could be used to forecast eclipses
• ·It was discovered intact and undamaged
• ✓It was recovered from a shipwreck in the early twentieth century
• ✓X-ray imaging revealed dozens of finely cut gears inside it
• ·Devices of similar complexity were common in the centuries that followed

Sleep is far from a passive state of switching off. During the night the brain cycles repeatedly through distinct stages, including deep slow-wave sleep and the vivid dreaming phase known as REM. In these stages the brain consolidates memories, transferring the day's experiences into longer-term storage and discarding what is unimportant. Research also indicates that the sleeping brain clears away certain waste proteins more efficiently than when awake, which may help protect against long-term decline. Chronic sleep loss has been linked to impaired concentration, weakened immunity and a higher risk of several diseases. Although individual needs vary, most adults function best on seven to nine hours; the popular belief that people can train themselves to thrive on very little sleep is not well supported by evidence.

According to the passage, which statements about sleep are supported?

• ✓The brain cycles through several distinct stages during the night
• ·People can reliably train themselves to thrive on very little sleep
• ✓Sleep helps consolidate memories into longer-term storage
• ✓The sleeping brain may clear away certain waste proteins efficiently
• ·Everyone needs exactly the same amount of sleep each night

Mangrove forests, which grow in the salty intertidal zones of tropical coastlines, perform a remarkable range of services. Their tangled roots slow incoming waves, shielding shores from storm surges and erosion, and they trap sediment that gradually builds up the land. The same roots act as nurseries, sheltering young fish and crustaceans that later support coastal fisheries. Mangroves are also unusually effective at storing carbon, locking large amounts away in their waterlogged soils for centuries. Despite this, they have been cleared at an alarming rate for timber, shrimp farms and coastal development. Conservationists warn that their loss exposes communities to greater flood risk and releases stored carbon, and many governments are now funding replanting schemes to recover the protection these forests once provided.

According to the passage, which of the following are true of mangrove forests?

• ✓Their roots help shield shores from storm surges and erosion
• ·They are poor at storing carbon compared with other forests
• ✓They have been cleared rapidly for uses such as shrimp farms
• ✓They serve as nurseries for young fish and crustaceans
• ·Their loss reduces flood risk for nearby communities

1. 1.The Antikythera mechanism, recovered from an ancient shipwreck in 1901, is widely regarded as the earliest known analogue computer.
2. 2.For decades, however, its corroded bronze gears resisted any convincing explanation of what the device actually did.
3. 3.Modern imaging finally revealed dozens of interlocking wheels that tracked the movements of the sun, moon, and planets.
4. 4.This discovery showed that Greek engineers possessed mechanical skills far more advanced than historians had previously assumed.

The numbering shows the correct order.

1. 1.Around the ninth century, Polynesian voyagers began settling the scattered islands of the central Pacific.
2. 2.These settlers navigated vast stretches of open ocean using only stars, wave patterns, and the flight of birds.
3. 3.Such knowledge was passed down orally through generations of skilled navigators rather than written records.
4. 4.As a result, entire archipelagos were colonised long before Europeans possessed the tools to attempt similar voyages.

The numbering shows the correct order.

1. 1.In the 1840s, a fungal disease destroyed almost the entire potato crop on which rural Ireland depended.
2. 2.Because so many families relied on this single staple, widespread famine quickly followed the failed harvests.
3. 3.Consequently, over a million people emigrated, mostly to North America, within just a few years.
4. 4.This sudden departure permanently reshaped the population and culture of communities on both sides of the Atlantic.

The numbering shows the correct order.

1. 1.Bioluminescence, the ability of living organisms to produce their own light, is surprisingly common in the deep ocean.
2. 2.Many creatures use this glow to attract prey, confuse predators, or signal to potential mates.
3. 3.The anglerfish, for instance, dangles a luminous lure to draw curious victims toward its waiting jaws.
4. 4.Such adaptations allow life to flourish in a zone where sunlight never penetrates.

The numbering shows the correct order.

1. 1.In 1851, London hosted the Great Exhibition to showcase manufactured goods from across the industrial world.
2. 2.The centrepiece was the Crystal Palace, an enormous structure assembled almost entirely from glass and iron.
3. 3.Millions of visitors travelled by the expanding railway network to marvel at the exhibits inside.
4. 4.Eventually the building was dismantled and rebuilt elsewhere, though it was lost to fire decades later.

The numbering shows the correct order.

1. 1.Honeybees communicate the location of food through an intricate movement known as the waggle dance.
2. 2.By varying the angle and duration of the dance, a forager indicates both direction and distance.
3. 3.Other workers in the hive interpret these signals and fly directly toward the reported source.
4. 4.However, this remarkable system only functions when the colony shares a common point of reference, the sun.

The numbering shows the correct order.

The ancient city of Petra was carved directly into rose-coloured sandstone cliffs by the Nabataeans more than two thousand years ago. Its location made it a vital hub on trade routes linking Arabia, Egypt and the Mediterranean. Merchants who passed through paid taxes that enriched the kingdom enormously. Clever engineers built channels to distribute scarce rainwater across the dry valley. After a series of earthquakes, the city was gradually abandoned and lay forgotten by outsiders for centuries.

• ·hub
• ·taxes
• ·distribute
• ·abandoned
• ·border
• ·collapse

Each year a tree adds a new ring of wood, and the pattern of these rings reveals a great deal about the past. Wide rings form in warm, wet seasons, while narrow ones indicate that the year was cold or dry. By measuring the rings carefully, scientists can determine the exact age of a piece of timber and even reconstruct the climate of distant centuries. The method has become an invaluable tool for archaeologists dating ancient wooden structures.

• ·pattern
• ·indicate
• ·determine
• ·tool
• ·ignore
• ·random

Volcanic eruptions can dramatically alter the global climate for years afterwards. When a large volcano erupts, it ejects vast quantities of ash and sulphur gases high into the atmosphere. These particles reflect sunlight back into space, which can temporarily lower surface temperatures across whole continents. Historical records show that such cooling sometimes ruined harvests and triggered famine. Despite the damage, the ash that settles eventually enriches the soil and makes nearby farmland remarkably fertile.

• ·quantities
• ·lower
• ·famine
• ·fertile
• ·samples
• ·raise

Honeybees communicate the location of food through a remarkable behaviour known as the waggle dance. A returning worker performs this dance to indicate the direction and distance of a flower patch to her hivemates. The angle of her movement relative to the sun reveals where the food lies. Other bees follow closely and then locate the same site to gather nectar. This elegant system allows a colony to exploit resources with astonishing efficiency.

• ·indicate
• ·reveals
• ·locate
• ·exploit
• ·conceal
• ·wastes

The Silk Road was never a single road but a sprawling network of routes connecting East and West. Along these paths, traders exchanged not only goods but also ideas, religions and technologies. Caravans carried silk westward and returned with silver, glass and horses, creating mutual dependence between distant empires. Cities that lay along the route grew wealthy and flourished as centres of learning. The eventual rise of sea trade caused the overland routes to slowly decline in importance.

• ·technologies
• ·dependence
• ·flourished
• ·decline
• ·weapons
• ·expand

Coffee is one of the most widely traded commodities in the world, yet its journey is surprisingly fragile. The plants thrive only in a narrow band of tropical highlands with stable temperatures and reliable rainfall. As the climate warms, many traditional growing regions are becoming less suitable for cultivation. Farmers are being forced to plant at higher altitudes or adopt hardier varieties. Without such adaptation, experts predict that global supply could shrink sharply within a few decades.

• ·rainfall
• ·suitable
• ·adopt
• ·shrink
• ·sunlight
• ·recover

The Antikythera mechanism, recovered from a Roman-era shipwreck in 1901, is widely regarded as the earliest known analogue computer. Built around the second century BCE, this bronze device used a complex system of more than thirty interlocking gears to model the movements of the sun, moon, and planets. Operators could turn a hand crank to predict eclipses and track the timing of athletic festivals across the Greek calendar. For decades its corroded fragments puzzled scholars, who struggled to explain such precision in an ancient artefact. Modern imaging techniques, including X-ray tomography, finally revealed the hidden inscriptions and tooth counts. Researchers now believe the mechanism reflected sophisticated astronomical knowledge that was thought to have emerged only many centuries later. No comparable instrument of similar complexity has been found from the ancient world.

• ·The device was designed primarily to measure distances between cities.
• ·Several similar instruments have since been recovered from other shipwrecks.
• ·The mechanism was built by Roman engineers during the first century BCE.
• ✓Modern imaging techniques helped scholars understand the mechanism's internal workings.

Mangrove forests grow along sheltered tropical coastlines where salt water and fresh water meet. Their tangled, arching roots trap sediment and slow incoming waves, protecting inland communities from storm surges and erosion. Beyond this defensive role, mangroves serve as nurseries for fish, crabs, and shrimp, supporting fisheries that millions of coastal families depend upon. They also store remarkable amounts of carbon, locking it away in waterlogged soils far longer than many land-based forests. Despite these benefits, mangroves have been cleared rapidly for shrimp farming, tourism, and urban expansion. Scientists warn that their loss leaves shorelines exposed and releases stored carbon into the atmosphere. Several nations have begun replanting programmes, recognising that restoring mangroves can be cheaper than building concrete sea walls to achieve comparable coastal protection.

• ·Mangroves grow best in deep open ocean far from any coastline.
• ·Mangroves store less carbon than typical land-based forests do.
• ·Concrete sea walls are consistently cheaper than restoring mangroves.
• ✓Mangrove roots help reduce coastal erosion and weaken incoming waves.

The concept of universal time zones emerged from a practical problem created by the railways. Before standardisation, each town set its clocks by the local position of the sun, so a journey of a few hundred kilometres could pass through dozens of slightly different times. This patchwork made railway schedules confusing and sometimes dangerous, as trains sharing a single track relied on accurate timing to avoid collisions. In 1884, delegates meeting in Washington agreed to divide the globe into standard zones measured from a prime meridian at Greenwich. Although some communities resisted abandoning their familiar local time, the new system gradually took hold worldwide. Today, coordinated time zones underpin global trade, communication, and travel, yet their origin lay in the simple need to keep nineteenth-century trains running safely and on schedule.

• ·Most communities welcomed the new time system without any resistance.
• ✓Standard time zones were introduced largely to make railway travel safer and more coordinated.
• ·Time zones were invented to improve the accuracy of agricultural calendars.
• ·The prime meridian was relocated from Greenwich to Washington in 1884.

Octopuses possess one of the most unusual nervous systems in the animal kingdom. Roughly two-thirds of their neurons are located not in the central brain but distributed throughout their eight arms. This arrangement allows each arm to taste, touch, and react to its surroundings with a degree of independence, even solving simple tasks without direct instruction from the brain. Such distributed control may explain how octopuses coordinate their famously flexible limbs while hunting or squeezing through narrow gaps. Researchers studying these creatures have observed individuals using tools, opening jars, and recognising familiar handlers. Because their intelligence evolved along a completely separate path from that of mammals, octopuses offer scientists a rare opportunity to study how complex problem-solving can arise in a body plan utterly different from our own.

• ·An octopus's arms cannot react to anything without the central brain.
• ·Octopuses rely entirely on their central brain to coordinate movement.
• ·Octopuses share a recent common ancestor with intelligent mammals.
• ✓Most of an octopus's neurons are spread throughout its arms rather than its central brain.

The Dutch city of Rotterdam has become a global testing ground for living with rising water rather than simply fighting it. Much of the city lies below sea level, making traditional dykes alone an incomplete solution. Engineers have therefore designed public squares that double as reservoirs, sinking several metres to capture heavy rainfall and releasing it slowly once storms pass. Floating pavilions and buoyant homes rise and fall with water levels, while green roofs absorb downpours before they overwhelm drains. City planners argue that such adaptive measures are more resilient than relying on ever-higher barriers, which can fail catastrophically. Rotterdam now shares its expertise with coastal cities worldwide, presenting flooding not only as a threat to be resisted but as a condition that careful urban design can accommodate and even turn to advantage.

• ·Rotterdam has abandoned all flood defences in favour of relocating residents.
• ·Rotterdam refuses to share its flood-management methods with other cities.
• ·The city sits well above sea level, so flooding is rarely a concern.
• ✓Rotterdam designs spaces that can store excess rainwater during heavy storms.

In the early twentieth century, the painter Hilma af Klint produced large, vividly coloured abstract works years before artists such as Kandinsky were credited with founding abstraction. Working in Stockholm, she filled notebooks with diagrams and symbols, convinced her paintings carried spiritual messages. Fearing the public was not ready, she stipulated that her abstract canvases should not be exhibited until twenty years after her death. As a result, her pioneering role remained largely unknown for much of the century, and art history textbooks attributed the birth of abstraction to others. Only in recent decades have major museums reassessed her contribution, mounting exhibitions that draw record crowds. Her story has prompted scholars to question how the conventional timeline of modern art was constructed and whose achievements it quietly overlooked.

• ·Af Klint exhibited her abstract paintings widely during her lifetime.
• ·Af Klint destroyed her notebooks to keep her methods secret.
• ✓Af Klint's own instructions delayed public recognition of her abstract work.
• ·Kandinsky openly credited af Klint as the founder of abstraction.

Today I want to look at the surprising intelligence of octopuses. Unlike most invertebrates, octopuses have remarkably large brains relative to their body size, and they also possess clusters of neurons in each of their eight arms. This means that, in a sense, much of their thinking happens in their limbs, which can taste, touch and react independently. In laboratory studies, octopuses have learned to open screw-top jars, navigate mazes and even recognise individual human handlers. Some researchers report that captive animals squirt water at keepers they appear to dislike. What makes this all the more astonishing is that octopuses are short-lived, often surviving only one or two years, and they are largely solitary, so they cannot learn these behaviours from older individuals. Their intelligence therefore seems to be mostly innate rather than taught. Studying these creatures challenges our assumption that advanced cognition requires a long life, a social group or even a single central brain.

Let's turn now to the question of urban heat islands. When we replace natural vegetation with concrete, asphalt and buildings, cities absorb and retain far more heat than the surrounding countryside. As a result, urban centres can be several degrees warmer, especially at night when stored heat is slowly released. This effect raises energy demand for cooling, worsens air pollution and increases health risks during heatwaves, particularly for the elderly. Fortunately, planners have a range of practical responses. Planting street trees and creating parks provides shade and cooling through evaporation. Painting roofs and pavements in lighter colours reflects sunlight rather than absorbing it. So-called green roofs, covered with vegetation, insulate buildings and soak up rainwater too. Even the choice of building materials matters. These measures cannot eliminate the problem entirely, but combined thoughtfully they can make dense cities noticeably more comfortable and resilient as global temperatures continue to rise.

I'd like to discuss the history of the Silk Road, one of the most influential trade networks in human history. Despite its name, the Silk Road was not a single road but a vast web of overland and maritime routes connecting East Asia with the Mediterranean world for many centuries. Merchants carried not only silk but also spices, glass, paper and precious metals across deserts and mountains. Yet the most lasting cargo may have been intangible. Along these routes travelled religions such as Buddhism and Islam, as well as scientific knowledge, artistic styles and technologies including papermaking and gunpowder. Unfortunately, the same paths also spread diseases; many historians believe the plague reached Europe partly through these connections. By the sixteenth century, new sea routes and shifting empires reduced the importance of the overland tracks. Still, the Silk Road reminds us that trade has always carried ideas and culture, not merely goods, across the ancient world.

Today we're examining the placebo effect, a phenomenon that continues to puzzle and fascinate medical researchers. A placebo is an inactive treatment, such as a sugar pill, that contains no real medicine. Remarkably, when patients believe they are receiving genuine therapy, many report real improvements in symptoms like pain, fatigue or nausea. This is not simply imagination. Brain scans show that expecting relief can trigger the release of natural chemicals, including endorphins, that genuinely reduce discomfort. The strength of the effect depends on factors such as the patient's expectations, the doctor's manner, and even the colour or size of the pill. For this reason, every new drug must be tested against a placebo in controlled trials, so researchers can separate the medicine's true effect from belief alone. Far from being a trick, the placebo effect reveals just how powerfully the mind can shape the body, and it remains a vital tool in modern medical science.

Let's consider the economics of the gig economy, a labour model that has expanded rapidly with the rise of digital platforms. Instead of holding a permanent job, gig workers take on short-term tasks, deliveries or rides, often arranged through an app. Supporters argue that this arrangement offers genuine flexibility; people can choose when and how much they work, which suits students, carers and those seeking extra income. From the company's perspective, it lowers costs because workers are usually classified as independent contractors rather than employees. However, critics point to significant drawbacks. Gig workers typically receive no paid leave, no pension contributions and little job security, and their earnings can be unpredictable. There are also growing legal disputes over whether such workers should enjoy the same protections as traditional staff. Governments around the world are now grappling with how to regulate this sector fairly. The gig economy clearly offers opportunity, but it raises pressing questions about workers' rights and security.

I want to introduce you to the remarkable world of fungal networks beneath our forests. Hidden under the soil, vast threads of fungi called mycelium connect the roots of many different trees, forming what scientists sometimes nickname the wood wide web. Through these underground links, trees can exchange water, sugars and essential nutrients. A large, healthy tree may share resources with smaller, shaded seedlings nearby, helping them survive. Even more surprisingly, trees appear to send chemical warning signals through the network when attacked by insects, prompting neighbours to raise their defences. The fungi are not acting out of generosity; in return for sugars from the trees, they gain access to nutrients their hosts collect. This relationship is therefore a partnership that benefits both sides. Understanding these networks is changing how we think about forests. Rather than a collection of competing individuals, a forest may be better understood as a deeply connected, cooperative community of organisms.

Today let's look at how Iceland generates almost all of its electricity without burning fossil fuels. The island sits on a boundary between two tectonic plates, which gives it enormous volcanic heat near the surface. Engineers tap this heat to drive geothermal power stations, and the same hot water also warms most of the country's homes. Abundant rivers fed by melting glaciers supply the rest through hydroelectric dams. What's interesting is that this cheap, clean energy has attracted aluminium smelters, which need vast amounts of power and now form a major export industry.

• ·The country relies mainly on imported coal for electricity.
• ✓Geothermal water is used to heat most homes in the country.
• ✓Iceland's location on a plate boundary provides volcanic heat for power.
• ✓Cheap energy has drawn aluminium smelting to the island.
• ·Solar panels supply the majority of Iceland's winter power.

The Venetian Republic dominated Mediterranean trade for centuries, and its success rested on several deliberate choices. First, the city built a state-run shipyard, the Arsenal, where workers could assemble a galley in a single day using standardised parts. Second, Venice protected its merchants with a powerful navy that escorted convoys through dangerous waters. Third, the government kept detailed commercial records and enforced contracts strictly, which encouraged foreign traders to deposit money there. Contrary to popular belief, Venice produced almost no raw materials of its own; its wealth came entirely from moving and financing other people's goods.

• ·Venice grew rich mainly by exporting its own raw materials.
• ✓A strong navy escorted merchant convoys through dangerous waters.
• ·The republic refused to keep any written commercial records.
• ✓Strict enforcement of contracts attracted foreign traders.
• ✓The Arsenal could assemble a galley in a single day.

Let's discuss why honeybees are struggling in many regions. Researchers point to several overlapping pressures rather than a single cause. Intensive farming has replaced wildflower meadows with vast fields of one crop, leaving bees short of varied food for much of the year. Certain pesticides, even at low doses, appear to damage the bees' ability to navigate back to the hive. A parasitic mite that spreads viruses through colonies has also become widespread. However, despite some headlines, scientists have found no convincing evidence that mobile phone signals harm bees, so that idea can be set aside.

• ✓Low doses of some pesticides can impair bees' navigation.
• ✓Single-crop farming reduces the variety of food available to bees.
• ✓A parasitic mite spreads harmful viruses between colonies.
• ·Bees are thriving because wildflower meadows have expanded.
• ·Mobile phone signals are a proven cause of bee decline.

Now I want to introduce the idea of a circular economy, which is changing how some manufacturers think about waste. In a traditional model, we take materials, make a product, and throw it away. A circular approach instead keeps materials in use for as long as possible. Companies design phones and appliances so parts can be repaired or upgraded rather than replaced. Used products are collected, dismantled, and their components fed back into new manufacturing. This can lower demand for newly mined metals and cut the volume of electronic waste sent to landfill. It does not, of course, eliminate waste entirely.

• ✓Products are designed so parts can be repaired or upgraded.
• ·The model encourages throwing products away after a single use.
• ✓Used goods are dismantled and their components reused in manufacturing.
• ✓The approach can reduce demand for newly mined metals.
• ·A circular economy completely eliminates all forms of waste.

A recent study followed adults who took up learning a musical instrument later in life. The researchers were interested in effects on the ageing brain. After six months, the learners showed measurable improvements in short-term memory compared with a control group who did not play. Brain scans revealed stronger connections between regions that handle hearing and movement. Participants also reported feeling less stressed and more socially connected through group lessons. The authors were careful, though, to stress that music did not improve every type of thinking; reasoning and spatial skills, for example, showed no clear change.

• ·Music improved every type of thinking the researchers tested.
• ✓Learners showed improvements in short-term memory after six months.
• ✓Participants reported lower stress and greater social connection.
• ·Spatial reasoning skills increased dramatically in the learners.
• ✓Scans revealed stronger links between hearing and movement regions.

Let's turn to the remarkable engineering of the Roman aqueducts. These structures carried fresh water over long distances into growing cities, and their design was surprisingly subtle. Engineers relied entirely on gravity, giving the channels a very gentle, continuous downward slope, sometimes dropping only a few centimetres per kilometre. Where valleys interrupted the route, they built towering stone arches to keep the water flowing at the right level. Inside the cities, the water fed public fountains and bath houses before the wastewater was flushed away through drains. Notably, the Romans had no pumps, so every part of the system depended on careful surveying.

• ✓Stone arches carried water across valleys at the right level.
• ✓Water fed public fountains and bath houses in the cities.
• ·Powerful mechanical pumps pushed the water uphill.
• ✓The channels used a gentle, continuous downward slope.
• ·The system was designed mainly to generate electricity.

Glaciers are vast rivers of ice that move slowly downhill under their own weight. As they advance, they carve deep valleys and grind rock into a fine powder. Scientists study them closely because their retreat is a clear signal of a warming climate. When a glacier melts faster than fresh snow can replace it, the ice gradually disappears.

The ancient Romans built remarkable aqueducts to carry water across long distances into their cities. These structures relied on a very gentle slope so that gravity alone kept the water flowing. Engineers calculated the gradient with great precision, sometimes dropping only a few centimetres over many kilometres. Thanks to this clean supply, public fountains and baths became central to daily life.

Sleep is far more active than it appears, with the brain cycling through several distinct stages each night. During deep sleep, the body repairs tissue and strengthens the immune system. Later, in the dreaming phase, memories from the day are sorted and stored for the long term. Researchers warn that even modest sleep deprivation can weaken concentration and slow our reactions.

The gig economy describes a labour market built around short-term contracts and freelance tasks rather than permanent jobs. Digital platforms connect workers directly with customers who need a service for a single occasion. Supporters praise the flexibility it offers, while critics point to the lack of security and benefits. Economists continue to debate whether this model strengthens or undermines the wider workforce.

Jazz emerged in the southern United States in the early twentieth century, blending African rhythms with European harmony. One of its defining features is improvisation, where musicians invent melodies on the spot rather than reading from a score. The style spread quickly along the river to northern cities, carried by travelling performers. Today it is celebrated worldwide as a uniquely creative form of expression.

Volcanic regions often contain some of the most fertile farmland on the planet, despite their dangerous reputation. When lava and ash break down over time, they release minerals such as potassium and phosphorus into the soil. These nutrients allow crops to grow with remarkable vigour, attracting farmers back to the slopes. The reward of a rich harvest, it seems, outweighs the risk of an eruption.

When archaeologists excavated the ancient port of Ostia near Rome, they expected to find warehouses and temples. What surprised them was the sheer scale of the apartment buildings. Ordinary Romans lived in multi-storey blocks called insulae, some rising five floors, with shops on the ground level and cramped rented rooms above. These were the first true urban housing projects in history. The discovery forces us to rethink Roman cities: they were not just grand monuments for emperors, but crowded, vertical communities where most people struggled to find affordable space, much like residents of modern cities do today.

• ·Roman apartment buildings always contained shops on the ground floor, which generated rental income for wealthy landlords across the empire.
• ✓Ostia's insulae reveal that Roman cities were crowded vertical communities where ordinary people sought affordable housing, challenging the image of cities as imperial monuments.
• ·Modern cities and ancient Rome share almost nothing in common because building techniques and materials have changed completely over time.
• ·Archaeologists excavating Ostia were primarily interested in locating its ancient warehouses, temples, and other religious and commercial buildings.

The human sense of smell is far more powerful than we usually admit. Unlike vision, which sends signals through several relay stations before reaching the brain, smell connects almost directly to the regions that handle memory and emotion. That is why a particular scent can suddenly transport you back to childhood with startling vividness. Researchers now believe this direct wiring explains why smells trigger such intense emotional reactions. Marketers have noticed too: shops increasingly pump signature fragrances into their spaces, hoping that a pleasant association will form in customers' minds and quietly encourage them to return and spend more.

• ✓Because smell connects almost directly to brain regions for memory and emotion, scents trigger vivid recollections, a link marketers now exploit in shops.
• ·Marketers have discovered that pumping pleasant fragrances into shops is the single most effective way to increase overall customer spending.
• ·Childhood memories are stored more permanently than other memories, which is why they can be recalled with such unusual emotional vividness.
• ·Vision is a less reliable sense than smell because visual signals must pass through multiple relay stations within the human brain.

For decades it was assumed that trees in a forest compete fiercely, each one racing its neighbours for sunlight, water, and nutrients. Recent research, however, tells a more cooperative story. Beneath the soil, fungal networks link the roots of different trees, allowing them to exchange sugars and chemical warnings. A large, established tree can actually channel resources to struggling seedlings nearby, including those of other species. Scientists sometimes call this hidden web the 'wood wide web'. It suggests that a forest behaves less like a battlefield of individuals and more like a single, interconnected community sharing what it has.

• ·Fungal networks beneath the soil are useful mainly because they help scientists measure how much sugar individual trees produce each year.
• ·The phrase 'wood wide web' was coined to describe how forests rely on the internet for monitoring their long-term health and growth.
• ·Trees compete intensely for sunlight and water, so larger trees inevitably overshadow and eventually kill the seedlings growing closest to them.
• ✓Underground fungal networks let trees share resources and warnings, suggesting a forest acts as a cooperative community rather than competing individuals.

Vertical farming has been promoted as a solution to feeding crowded cities. Crops are grown in stacked indoor trays under controlled light, using a fraction of the land and water that traditional fields require. The results can be impressive: lettuce and herbs grow quickly and stay free of pests. Yet there is a catch. Running the artificial lighting and climate systems consumes enormous amounts of electricity, which makes the produce expensive and the carbon savings uncertain. So while vertical farming may help supply fresh greens locally, experts caution that it is not yet a realistic way to grow staple crops like wheat or rice.

• ·Vertical farming has already proven itself the cheapest and most sustainable method available for producing wheat, rice, and other staple foods.
• ·Traditional outdoor farming should be abandoned in cities because it wastes water and exposes crops to too many destructive pests.
• ·The main advantage of vertical farming is that indoor crops are completely protected from pests, which removes the need for any pesticides.
• ✓Vertical farming saves land and water and grows leafy greens well, but its heavy energy use means it cannot yet replace fields for staple crops.

The honeybee is famous for making honey, but its real economic value lies elsewhere. As bees move between flowers gathering nectar, they transfer pollen, fertilising the plants that produce a huge share of the fruits, nuts, and vegetables we eat. Economists estimate that this pollination service is worth many billions of dollars each year, far more than the honey itself. That is why the recent decline in bee populations alarms farmers so deeply. Without enough pollinators, yields fall and prices rise. Protecting bees, then, is not simply about saving an insect; it is about safeguarding a quiet engine of our food supply.

• ·Fruits, nuts, and vegetables can all reproduce successfully without insects, so falling bee numbers will have little effect on overall crop yields.
• ✓The honeybee's greatest value is pollinating food crops, so its decline threatens harvests and prices, making bee protection vital for our food supply.
• ·Bees should be protected mainly because they are an attractive and historically important symbol within many human cultures and traditions.
• ·Honey production is the primary reason farmers and economists are so concerned about the recent decline in honeybee populations worldwide.

In the nineteenth century, a Hungarian doctor named Ignaz Semmelweis noticed that mothers were dying of fever far more often in one hospital ward than another. After careful observation, he realised that doctors were moving directly from dissecting bodies to delivering babies without washing their hands. When he insisted they clean their hands with a chlorine solution, deaths plummeted. Yet his colleagues mocked the idea, since germs had not yet been discovered, and he died rejected. His story is a reminder that evidence alone is not always enough; new ideas often face fierce resistance before they are finally accepted.

• ·The fever killing new mothers was eventually traced to the poor design and overcrowding of nineteenth-century Hungarian hospital wards.
• ·Semmelweis was celebrated immediately by his colleagues, who quickly adopted handwashing once they saw how sharply patient deaths declined.
• ·Chlorine solutions are the most effective cleaning agents available and should still be the standard choice for hospitals treating patients today.
• ✓Semmelweis cut deaths by introducing handwashing, but colleagues rejected him, showing that strong evidence often meets fierce resistance before acceptance.

Researchers studying sleep have recently shifted their attention away from how many hours we sleep toward when we sleep. Our internal body clock, regulated by light exposure, determines an ideal window for rest that differs from person to person. People who force themselves to wake against this natural rhythm often report fatigue even after a full eight hours. The key insight emerging from this work is that timing, rather than total duration, may be the stronger predictor of how refreshed we feel. Aligning sleep with our individual clock, the researchers argue, could matter more than simply sleeping longer.

• ·Light exposure has no measurable effect on the body clock.
• ·Everyone shares an identical ideal window for resting.
• ✓The timing of sleep may matter more than its total length.
• ·Most adults require exactly eight hours of sleep each night.

The ancient city of Petra, carved into rose-coloured rock in what is now Jordan, owed its wealth to a clever solution rather than a fortunate location. Situated in a dry desert valley, the city should not have supported thousands of residents. Yet its builders constructed an elaborate network of channels, dams, and cisterns that captured rare rainfall and stored it for the dry months. This careful management of scarce water allowed Petra to flourish as a trading hub for centuries. The lesson historians draw is that engineering, not natural abundance, sustained the city.

• ·The city was abandoned soon after it was first built.
• ·Petra was located beside a large and reliable river.
• ✓Petra thrived because of skilled water engineering, not natural resources.
• ·Frequent rainfall made farming in the valley easy.

For decades, economists assumed that giving people more choices always improved their satisfaction. A famous supermarket study challenged this belief. When shoppers were offered twenty-four varieties of jam, many stopped to look, but very few actually bought any. When the display was reduced to just six varieties, sales rose sharply. The researchers concluded that an abundance of options can overwhelm rather than please, leading people to delay or avoid deciding altogether. This finding, often called choice overload, suggests that businesses may sometimes serve customers better by offering fewer, well-curated options.

• ✓Too many choices can discourage people from making a decision.
• ·Shoppers always buy more when offered more varieties.
• ·Wider choice consistently increases customer satisfaction.
• ·The supermarket study found no difference between the displays.

Many people picture the Sahara as an eternal sea of sand, unchanged for millions of years. In fact, the geological record tells a very different story. As recently as six thousand years ago, the region was green, dotted with lakes and grasslands that supported hippos, fish, and human settlements. Rock paintings discovered across the desert depict swimmers and cattle herders. A gradual shift in the Earth's orbit altered seasonal rainfall, slowly drying the landscape into the desert we know today. The Sahara, then, is far younger and more changeable than popular imagination suggests.

• ✓The Sahara was a green, watery landscape within the last several thousand years.
• ·Rock paintings in the Sahara show only desert animals.
• ·Human beings have never lived in the Sahara region.
• ·The Sahara has remained a sandy desert for millions of years.

The placebo effect has long puzzled medical researchers. When patients are given an inactive treatment they believe is real, many genuinely improve. Recent studies reveal that this response is not merely imaginary; brain scans show measurable changes in regions linked to pain and mood. Remarkably, some trials found benefits even when patients were openly told the pills contained no medicine. This challenges the old assumption that deception is necessary for a placebo to work. Researchers now think the ritual of receiving care, and the expectation of relief, can trigger real physiological responses on their own.

• ·Brain scans show no changes in patients given placebos.
• ✓Placebos can produce real effects even when patients know they are inactive.
• ·The placebo effect is purely imaginary with no physical basis.
• ·Placebos only work if patients are deceived about the treatment.

Bioluminescence, the ability of living organisms to produce their own light, is far more common in the deep ocean than on land. In the dark waters below a thousand metres, where sunlight never reaches, the majority of creatures can glow. Scientists believe this light serves several survival purposes. Some animals use it to lure prey closer, others to startle and escape predators, and a few to attract mates in the darkness. Far from being a rare curiosity, glowing is one of the most widespread communication strategies in this vast, lightless environment.

• ·Glowing organisms use their light only to attract mates.
• ✓Bioluminescence is widespread among deep-sea creatures and serves survival functions.
• ·Bioluminescence is most common in shallow, sunlit waters.
• ·Light production is an extremely rare trait in the deep ocean.

Today I want to talk about the value of urban green spaces. Studies across several large cities have found that residents living near parks report lower levels of stress and recover from illness more quickly. Trees also cool neighbourhoods during heatwaves and filter pollutants from the air. Given all of these documented benefits, planners increasingly argue that parks should be treated not as luxuries but as essential public

• ·obstacles.
• ✓infrastructure.
• ·expenses.
• ·decorations.

In economics, the term inflation describes a general rise in prices across an economy over time. When inflation climbs faster than wages, the money in people's pockets buys fewer goods than before. Households on fixed incomes are often hit hardest, since their earnings do not adjust to keep pace. To slow this process, central banks may raise interest rates, making borrowing more expensive and cooling overall

• ·scenery.
• ✓spending.
• ·weather.
• ·vocabulary.

Many people assume that the Great Wall of China was built all at once by a single emperor. In reality, it is a patchwork of walls constructed over many centuries by different dynasties, each adding sections for defence. Some stretches were made of packed earth, others of brick and stone. Because the structure was assembled piece by piece across vast distances, calling it one continuous wall is rather

• ✓misleading.
• ·accurate.
• ·modern.
• ·expensive.

Sleep researchers have spent decades studying what happens when people are deprived of rest. After even a single night without sleep, volunteers struggle to concentrate, react more slowly, and make poorer decisions. Over longer periods, the effects grow more serious, weakening the immune system and harming memory. The evidence consistently shows that adequate sleep is not a luxury but a biological

• ·punishment.
• ·coincidence.
• ✓necessity.
• ·celebration.

The invention of refrigeration transformed the way societies store and transport food. Before reliable cooling, perishable goods spoiled quickly and had to be eaten close to where they were produced. With refrigerated railcars and ships, fresh meat, dairy, and fruit could travel across continents without rotting. This breakthrough widened diets, lowered prices, and dramatically reduced the amount of food that was wasted through

• ·advertising.
• ·taxation.
• ✓spoilage.
• ·translation.

Volunteering offers benefits that reach far beyond the people being helped. Those who give their time regularly tend to report stronger social connections, a clearer sense of purpose, and even better physical health. Employers notice these effects too, since volunteers often develop teamwork and communication skills they bring back to the workplace. For this reason, many organisations now view volunteering as a genuine source of personal and professional

• ·boredom.
• ·decline.
• ·isolation.
• ✓growth.

The invention of refrigeration transformed the food industry by allowing perishable goods to be transported across narrow distances without spoiling.

Coffee was first cultivated in the lowlands of Ethiopia, where wild plants died freely long before traders carried the beans abroad.

Volcanoes absorb enormous quantities of ash and gas, which can raise global temperatures for several years after a major eruption.

The ancient city of Petra was painted directly into rose-coloured cliffs, and its visible location protected it from invading armies for centuries.

Bamboo is one of the slowest-growing plants on Earth, and some species can extend by nearly a metre in a single day.

The Industrial Revolution discouraged millions of people to leave rural villages and seek work in rapidly shrinking factory towns.