IELTS Academic Reading Practice Test 10

Every cup of tea, whether it is green, black or oolong, comes from the same plant: Camellia sinensis, an evergreen shrub native to the hills where south-western China meets north-eastern India and northern Myanmar. The plant prefers acidic soils and abundant rainfall, which is why many of the finest teas come from misty hillsides. Two main varieties are cultivated. The smaller-leaved Chinese variety tolerates cold winters, while the larger-leaved Assam variety thrives in hot, humid lowlands. Left unpruned, the plant can grow into a tree many metres tall, but on plantations it is kept at about waist height so that the young leaves and buds, which provide the best tea, can be picked easily.

Chinese legend credits the discovery of tea to the mythical emperor Shennong, who is said to have noticed leaves blowing into a pot of boiling water. The archaeological evidence is more modest but still impressive. In 2016 scientists reported that plant remains buried with Emperor Jing of the Han dynasty, who died in 141 BCE, were tea leaves, identified by chemical traces of caffeine and theanine. Because tea does not grow in the area around the tomb, near the modern city of Xi'an, the find also suggests that it was already being transported over long distances.

By the Tang dynasty (618–907 CE) tea had become a national drink in China. In the second half of the eighth century the scholar Lu Yu wrote The Classic of Tea, the first book devoted entirely to the subject, describing how it should be cultivated, processed and prepared. In Lu Yu's time, leaves were steamed, pounded and pressed into cakes, pieces of which were roasted, ground and boiled. Under the Song dynasty, powdered tea whisked into a froth with hot water became fashionable. Loose-leaf tea steeped in water, the method most familiar today, gained its dominance only under the Ming dynasty, after the first Ming emperor ordered in 1391 that tribute tea should be presented as loose leaves rather than compressed cakes.

Tea reached Japan with Buddhist monks who had studied in China. The monk Eisai, returning in 1191, is credited with introducing tea seeds and the Song method of preparing powdered tea, and with promoting the drink for its health benefits. Over the following centuries the preparation of powdered green tea developed into an elaborate ritual, the tea ceremony, which was refined in the sixteenth century by the tea master Sen no Rikyū and came to emphasise simplicity and harmony. The ritual was closely associated with Zen Buddhism, and its influence extended to Japanese architecture, ceramics and garden design.

Europeans first encountered tea through traders in Asia, and the Dutch were shipping it to Europe by the early seventeenth century. In England it became fashionable after 1662, when Charles II married the Portuguese princess Catherine of Braganza, a keen tea drinker. For most of the eighteenth century, however, heavy taxation made legally imported tea extremely expensive, and a large share of the tea consumed in Britain was smuggled. In 1784 the Commutation Act reduced the duty from 119 per cent to 12.5 per cent. This made smuggling unprofitable almost overnight and helped turn tea into an everyday drink for all social classes.

Britain's appetite for tea created a serious problem. China would accept little in exchange except silver, and the East India Company increasingly paid for tea with the proceeds of opium, which it sold illegally into China, a trade that eventually led to two wars. To reduce their dependence on China, the British sought to grow tea in their own territories. Native tea plants had been noticed in Assam in the 1820s, and plantations were established there. Between 1848 and 1851, the Scottish botanist Robert Fortune travelled in disguise through regions of China closed to foreigners, collecting thousands of tea plants and seeds for the East India Company. He also recruited skilled Chinese tea workers to pass on the techniques of processing.

Those techniques determine the type of tea. For green tea, the freshly picked leaves are heated soon after harvesting, by steaming or pan-firing, which deactivates the enzymes in the leaf and keeps it green. For black tea, the leaves are first left to wither and then rolled, breaking their cells and exposing their contents to the air.

The enzymes then drive a chemical reaction known as oxidation, which turns the leaves dark brown and creates a stronger flavour. The process is often described in the industry as fermentation, although no microorganisms are involved. Oolong teas are only partly oxidised. In the 1930s a machine-based method known as CTC, short for crush, tear, curl, was developed in Assam. It produces small, uniform particles that brew quickly, and it is still widely used for tea bags.

Tea is now the most widely consumed drink in the world after water, prepared in countless local styles, from Moroccan mint tea to the spiced milky tea of India. China is by far the largest producer, followed by India and Kenya, and the industry provides a livelihood for millions of people, many of them farming small plots of land. Yet the crop faces new challenges. Tea plants are sensitive to changes in temperature and rainfall, and growers in several regions have reported that shifting weather patterns are already affecting both the size and the quality of their harvests.

Few technologies have changed as rapidly over the past three decades as the wind turbine. Machines that once looked like experimental curiosities now stand in rows across hillsides, plains and shallow seas, and in 2024 they generated around 8 per cent of the world's electricity. In some countries the share is far higher: Denmark, which has played a central role in the industry's development, now obtains more than half of its electricity from the wind. In many parts of the world, wind farms on land are now among the cheapest ways of generating new electricity. Yet the basic idea of using moving air to do useful work is very old.

Windmills were grinding grain and pumping water in Persia more than a thousand years ago, and they spread across medieval Europe from the twelfth century. Using the wind to generate electricity, however, dates only from the late nineteenth century. In 1887 the Scottish engineer James Blyth built a turbine with cloth sails that lit his holiday cottage, and the following winter the American inventor Charles Brush constructed a far larger machine in Cleveland, Ohio, with a rotor of 144 wooden blades that charged batteries in the basement of his mansion. In Denmark during the 1890s, Poul la Cour used wind tunnels to show that rotors with a few fast-moving blades were more efficient than those with many slow ones.

The design that dominates today owes most to another Dane, Johannes Juul. His Gedser turbine, completed in 1957, had three blades and faced into the wind, features that remain standard on modern machines, and it operated for about a decade with little maintenance. Interest in wind power nevertheless remained limited while oil was cheap. It revived after the oil crises of the 1970s, and during the 1980s thousands of small turbines, many of them made in Denmark, were installed in wind farms in California, providing the industry with its first large market.

The physics of wind power explains why turbines have grown so large. The energy carried by moving air increases with the cube of its speed, so a doubling of the wind speed produces eight times as much power. The energy a turbine can capture also depends on the area swept by its blades, which increases with the square of their length. There is, however, a ceiling. In 1919 the German physicist Albert Betz showed that no turbine can extract more than about 59.3 per cent of the energy in the wind passing through it, since the air must keep moving to leave the rotor. Modern turbines approach this limit closely. They are mounted on tall towers because winds higher above the ground are both stronger and steadier.

The same logic has drawn developers out to sea. The world's first offshore wind farm, consisting of eleven small turbines, was built at Vindeby, off the Danish coast, in 1991. Offshore winds are generally stronger and more consistent than those on land, and turbines can be made much larger because their enormous blades and towers can be transported by ship rather than along roads. The costs of offshore wind fell sharply during the 2010s. In deep water, where fixing foundations to the seabed is impractical, turbines can now be mounted on floating platforms anchored to the seabed; the first floating wind farm began operating off the coast of Scotland in 2017.

The great challenge of wind power is its variability. A turbine produces electricity only when the wind blows within a certain range of speeds, and even good sites generate far less over a year than the turbine's maximum capacity would suggest. The ratio between a turbine's actual output and this theoretical maximum, known as its capacity factor, is typically higher offshore than on land. Electricity grids must therefore balance wind with other sources. Grid operators rely on increasingly accurate weather forecasts, on power stations that can be switched on quickly, on cables connecting neighbouring countries and, more and more, on large batteries. When the grid cannot absorb all the electricity available, turbines are sometimes deliberately switched off.

Wind farms also raise environmental and social concerns. Birds and bats are killed when they collide with blades, although the numbers vary greatly from one site to another. At the Smøla wind farm in Norway, researchers found that painting one of the three blades black, which makes the rotating blades easier for birds to see, reduced bird deaths by roughly 70 per cent, though the study involved only a few turbines. Some residents object to the noise and to the visual impact on the landscape. A further problem arises at the end of a turbine's life: its blades are made of composite materials that are difficult to recycle, and many have ended up in landfill sites, although manufacturers have begun to develop recyclable designs.

Over its whole life, however, a wind turbine is responsible for very low emissions of greenhouse gases, among the lowest of any source of electricity, and the energy used to manufacture and install it is typically repaid within a year or so of operation. With costs having fallen dramatically, the main obstacles to further growth are now less technical than practical: obtaining planning permission, building new transmission lines and finding the materials and skilled workers needed to construct turbines on an ever larger scale.

Of the roughly 7,000 languages spoken in the world today, a remarkable number are used by very few people. Just 23 languages account for more than half of the world's population, while thousands of others have fewer than 10,000 speakers each. Linguists estimate that around 40 per cent of all languages are now endangered. In 1992 the linguist Michael Krauss warned that as many as 90 per cent of the world's languages might be extinct or doomed by the end of the twenty-first century. Many specialists now regard that figure as too pessimistic, but few doubt that languages are being lost on a scale without historical precedent.

Languages rarely disappear because all their speakers die at once. Far more commonly, they fade through a process that linguists call language shift, in which a community gradually adopts another language, usually one associated with economic opportunity, education or political power. The decisive moment comes when parents stop passing the language on to their children. UNESCO's Atlas of the World's Languages in Danger classifies languages largely on this basis. Its categories range from vulnerable, where most children still speak the language but perhaps only in certain settings such as the home, to critically endangered, where the youngest speakers are grandparents and older, who use it only partially and infrequently.

It is tempting to describe language shift as a free choice made by people who see the advantages of a more widely spoken language. Sometimes it is. Historically, however, the choice was often anything but free. In many countries, Indigenous children were punished for speaking their own languages at school, and in some cases they were removed from their families and sent to residential schools designed to assimilate them. In Hawai'i, a law of 1896 made English the medium of instruction in schools, and within a few generations Hawaiian had almost ceased to be spoken by children. To present the outcome of such policies as the natural workings of a linguistic marketplace is, in my view, a serious distortion.

Why should the disappearance of a language concern anyone other than its speakers? One answer is scientific. Each language represents a distinct solution to the problem of human communication, and theories about what is possible in human language depend on the widest possible range of evidence; some languages, once documented, have turned out to have features that linguists had considered impossible. Another answer concerns knowledge. Languages spoken by small communities often contain detailed vocabularies for local plants, animals and environmental conditions, and this knowledge may be lost when speakers switch to a language that lacks such distinctions. The most important answer, however, is that for many communities a language is bound up with identity, history and a sense of belonging.

Not everyone accepts that the loss is a tragedy. Some commentators argue that fewer languages mean fewer barriers to trade and communication, and that individuals should be free to abandon a language that limits their prospects. There is something to this argument: no one should be compelled to preserve a language for the benefit of outside researchers. Its flaw lies in the assumption that people must choose between a minority language and a major one. Much of the world's population is multilingual, and there is little evidence that speaking an ancestral language at home prevents children from mastering a national or international language at school.

Revival is difficult but not impossible. The most celebrated case is Hebrew, which for centuries was used mainly in religious and scholarly contexts before being revived as an everyday spoken language from the late nineteenth century; it is now the first language of millions of people. In New Zealand, Māori communities established kōhanga reo, or language nests, from 1982, in which pre-school children are immersed in Māori by fluent elders, and the model inspired similar Hawaiian pre-schools from 1984. The Manx language of the Isle of Man lost its last native speaker, Ned Maddrell, in 1974, yet thanks to adult learners and a primary school that teaches through Manx, it is spoken once again by a new generation of children.

Where revival is not yet possible, documentation can at least preserve a record. Recordings of fluent speakers, together with dictionaries and grammars, may later allow a community to reclaim its language. Increasingly, linguists also train members of the communities concerned to make such recordings themselves. The Myaamia people of the American Midwest, whose language had no fluent speakers left by the middle of the twentieth century, have rebuilt it from written records compiled by missionaries and others, and children are once again learning it. Yet documentation is no substitute for a living speech community, and recordings stored in an archive do not, by themselves, keep a language alive.

What, then, should be done? The answer, I believe, must come from speech communities themselves. Outsiders, whether governments or linguists, can provide funding, training and official recognition, and they can end the policies that caused the damage in the first place. But they cannot decide on a community's behalf whether a language should be revived, nor what form that revival should take. The goal is not to freeze languages as museum pieces, but to ensure that the choice of whether to go on speaking them is a genuine one.