IELTS Academic Reading Practice Test 447

The Komodo dragon is the largest lizard alive today. Big males may reach three metres from snout to tail and weigh more than seventy kilograms. The species survives in the wild on only a handful of islands in eastern Indonesia, chiefly Komodo, Rinca and Flores. Its scientific name, Varanus komodoensis, comes from the island where European scientists first encountered it. Nothing quite like it lives anywhere else on Earth.

Rumours of a giant lizard reached Western scientists at the beginning of the twentieth century. A colonial official in the Dutch East Indies sent photographs and a skin to the zoological museum in Bogor. In 1912 the museum's director, Peter Ouwens, described the animal formally and gave it its scientific name. Fourteen years later an expedition led by W. Douglas Burden brought live specimens to the American Museum of Natural History in New York. Burden's expedition is often said to have inspired the film King Kong, although the connection is difficult to prove.

Komodo dragons inhabit dry, open country: savanna, monsoon forest and the scrub-covered lower slopes of hills. They are most active in the morning and late afternoon, and they retreat into burrows during the hottest part of the day to avoid overheating. The burrows are dug with the strong curved claws on their front feet. Adults are largely solitary, coming together mainly to feed or breed. A dragon hunts by ambush, waiting beside a game trail and then launching itself at a deer or a wild pig. For short distances it can run at around twenty kilometres an hour.

The body is covered in small tough scales, and plates of bone lie beneath the skin, giving it a rough, armoured quality. The teeth are curved and finely serrated, like the blade of a saw, and they are replaced throughout the animal's life.

Deer, wild pigs and water buffalo make up most of the diet, though dragons will also eat carrion, which they can locate by smell from several kilometres away. Their sense of smell depends on a long forked tongue. The tongue carries scent particles to a pair of organs in the roof of the mouth, and the animal flicks it out repeatedly as it walks. A large meal, once swallowed in pieces rather than chewed, is digested over several days. For many years it was thought that bacteria in the dragon's saliva killed an animal that escaped after a bite.

That belief was challenged in 2009, when a team led by Bryan Fry at the University of Melbourne reported venom glands in the lower jaw. In their view the venom, which causes blood pressure to fall and prevents clotting, is more important than bacteria in bringing down large prey. Other researchers have questioned how unusual the bacteria in a dragon's mouth really are. The argument between the two explanations is not yet settled.

Females become sexually mature at around five or six years of age. Mating takes place between May and August, and the female later lays about twenty eggs, which she buries in the ground or in a termite mound. Incubation lasts seven or eight months. The hatchlings are only about forty centimetres long, and they spend much of their first year in trees, where their climbing ability gives them some protection. Cannibalism of the young by adults is common, which may explain this behaviour.

In 2006 two female Komodo dragons kept in British zoos produced offspring without having mated with a male. The eggs developed by parthenogenesis, a form of reproduction in which an unfertilised egg begins to divide on its own. Several kinds of lizard are now known to do this, but the discovery was unexpected in an animal of such size. Some biologists have suggested that it could explain how a single female might establish a population on an island she reached by drifting on vegetation.

Komodo National Park was established in 1980, and the islands it protects were declared a World Heritage Site in 1991. Counting the animals is difficult, because they range widely and hide well, but surveys have pointed to a total of between three and five thousand in the wild. In 2021 the International Union for Conservation of Nature reclassified the species as endangered, citing the expected loss of coastal habitat as sea levels rise. Habitat loss on Flores, where dragons also live outside the park, is the main long-term concern.

Researchers have used radio transmitters and, more recently, satellite collars to follow individual animals, and camera traps have made it possible to survey remote valleys without capturing dragons at all. Tagging has shown that individual dragons occupy home ranges that overlap extensively. Rangers in the national park carry long forked sticks, since a dragon can move faster than a visitor expects. Tourism has grown steadily, particularly on Rinca and Komodo. The species has come through ice ages and rising seas, but whether it survives the next century will depend less on its own abilities than on decisions made by people far from Indonesia.

In open countryside, most rain either soaks into the soil or is taken up by plants, and only a fraction of it reaches a stream. In a city the position is reversed. Roofs, roads, pavements and car parks are built of materials that water cannot pass through. A heavy shower that would once have disappeared into the ground produces a surge of water within minutes. Engineers call this stormwater, and managing it has become one of the most expensive and least visible responsibilities of urban government.

The consequences are not confined to flooding. Water that races across asphalt picks up oil, particles of tyre rubber, zinc from roofs, fertiliser from gardens and microplastics, and carries them to the nearest river. Because the flow arrives suddenly and in a large volume, it also scours the bed of a stream, undercuts its banks and washes away the gravel in which fish lay their eggs. In many urban rivers the damage done by these surges is more serious than the pollution itself.

In older cities the problem is complicated by the design of the sewers. In the nineteenth century, engineers such as Joseph Bazalgette in London built systems that carried household sewage and rainwater in the same pipe, an arrangement known as a combined sewer. It works well in dry weather. After a heavy storm, however, the pipe is full, and the mixture of sewage and rain has to be discharged somewhere. The result is a combined sewer overflow, which releases untreated waste into a river or the sea. Cities from London to Chicago have spent billions trying to prevent it.

The traditional answer is to build bigger pipes and to store the excess until the treatment works can cope. Chicago's Tunnel and Reservoir Plan, begun in the 1970s, is one of the largest engineering projects of its kind. Deep tunnels cut through rock hold stormwater and sewage until it can be pumped to treatment plants. Detention basins, which are dry for most of the year and fill only after heavy rain, do the same job above ground.

Since the 1990s, however, attention has shifted towards methods that imitate the natural drainage of the landscape rather than replacing it. These approaches go by many names: sustainable drainage systems, or SuDS, in Britain; water-sensitive urban design in Australia; low-impact development in the United States; and sponge cities in China. The Chinese programme of pilot projects began in 2015. The labels differ, but the principle is the same. Rain is collected where it falls, held in soil and vegetation, and released slowly.

A rain garden is a shallow depression planted with species that tolerate both flooding and drought, into which the downpipe from a roof discharges. Permeable paving allows water to filter through joints or pores into a layer of gravel below. Green roofs of sedum or grass slow the flow and shade the building beneath them. Larger schemes use reed beds and constructed wetlands to clean the water as well as to store it, and a wetland can double as a park. New York has built a network of natural drainage corridors on Staten Island, and Philadelphia's long-term plan treats green infrastructure as a cheaper alternative to new tunnels.

Green infrastructure offers benefits that a pipe cannot. Vegetation cools the surrounding air, which matters in cities that are several degrees warmer than the countryside. It also provides habitat for insects and birds and makes streets more attractive, which in turn encourages people to walk. Cost comparisons usually favour it, although the calculations are awkward, because the benefits are spread across several departments while the costs fall on the water utility.

How well these systems perform over decades is less certain. Most monitoring has been carried out in temperate climates and over periods of only a few years. In cold cities the pores of permeable paving can clog with grit and freeze; in hot, dry ones the vegetation may die unless it is watered. The capacity of a rain garden depends on the soil beneath it, which varies from street to street. Maintenance is the weakest point of all: a system that nobody cleans will silt up. The cost then tends to fall on whoever owns it, which may be a householder who never wanted it.

Even the way the benefits are measured is disputed. Rainfall records are usually too sparse to show what happens in a single street, and computer models simplify both the ground and the drains. The 'first flush' — the idea that the first part of a storm carries most of the pollution — is often built into the design. Yet studies have found that the concentration of pollutants does not always peak at the start of a shower. Designers therefore work with wide margins of uncertainty.

None of this makes green infrastructure a bad idea. It means that a system has to be designed for the place where it is installed and maintained for as long as it is expected to work. As rainfall becomes more intense in many regions, the case for holding water where it falls grows stronger. The city that treats rain as a nuisance to be piped away is likely to spend more, in the end, than the city that treats it as a resource.

Requests to remove books from school libraries are not new, but they have become more frequent and better organised. For many years the American Library Association has recorded several hundred formal challenges annually, and in the present decade the number reported has risen sharply. A challenge is not the same as a ban: it is a request, usually from a parent, that a title be withdrawn from a shelf or restricted to older readers. Most challenges concern a small number of books, and most are resolved quietly, without publicity and without any change to the library.

Those who ask for a book to be removed generally speak for children they believe are too young for its content. They do not usually argue that a title should be banned everywhere, only that it is unsuitable for a particular age group or that it should be issued only with parental consent. Some parents contend that a school library is not a public library. It serves a captive audience of children, they point out, and the school has a duty of care that a municipal library does not. A graphic description of violence or sexual assault, they maintain, may distress a child who meets it unprepared.

Opponents of removal reply that the language of care is being used to justify censorship that would be unacceptable in any other institution. Their central argument is one of choice. Withdrawing a book, they say, takes that choice away from every family in the school, on the basis of a single complaint. A child who is not ready for a title can simply close it. School librarians make a related but narrower point: a library holds thousands of titles and no pupil reads them all. A decision not to buy a book is not the same as a decision to remove one. The question, the opponents insist, is not whether a book is good or bad, but who has the authority to decide what a child may read.

It is worth distinguishing between selection and removal. Every library selects. Librarians decide what to buy on the basis of reviews, the curriculum and a limited budget, and no library can hold everything. A decision not to buy a book is not censorship. A decision to take a book off the shelf because a group of parents objects to its content is a different matter. It overrides the professional judgement of the librarian and imposes one family's view on all the others.

Researchers who study adolescent reading are more cautious than campaigners on either side. They note that young people appear to benefit from meeting characters and situations unlike their own, and that fiction may support the development of empathy. But most such studies measure short-term changes of attitude in small groups, and it is difficult to show that a single novel produces a lasting effect. Claims that a particular book will corrupt a child, or enlighten one, are therefore untested in any strict sense, and the researchers themselves say so. Nor do the studies agree about which kinds of content are most likely to upset a young reader.

What matters most, in my view, is the procedure by which a complaint is handled. A school that removes a title in response to the first angry email rewards the loudest voice. A clearer system — a written form, a committee including a librarian and teachers, a published timetable and a right of appeal — protects everyone. It gives the complainant a fair hearing and it gives the book one too. Librarians report that most formal reviews end with the book remaining on the shelf, sometimes with a note about the ages for which it is suitable.

Age matters as well. A novel that is appropriate for a seventeen-year-old may be quite unsuitable for an eleven-year-old, and a library serving both is bound to be a compromise. Secondary schools commonly separate junior and senior collections, which is sensible as far as it goes, though it cannot resolve every case. It is striking that the titles most often challenged are frequently those that deal with race, sexuality or mental illness. Such subjects are ones that some teenagers need urgently to read about and may be unwilling to discuss with an adult.

There is a further cost that rarely appears in the statistics. Librarians and teachers report that repeated complaints make them cautious, and that they begin to avoid buying books that might attract attention. The effect is invisible, because a book that was never purchased leaves no record, but it is real, and it narrows what a school offers far more effectively than any individual removal. A climate in which every choice has to be defended is not one in which good collections are built.

My own position is that a school should rarely withdraw a book because of its content, and never merely because somebody has complained. Where age is genuinely the issue, it should restrict a title to older pupils and explain its decision publicly. The freedom to read is not a privilege that adults grant to children and may take back; it is a habit formed at school. A pupil who finds that a book has disappeared learns something about how far the school trusts its own students, and it is not a lesson that any school should wish to teach.