1、雅思（阅读）模拟试卷 84及答案与解析 0 You should spend about 20 minutes on Questions 1-13, which are based on Reading Passage 1 below. Astronaut ice cream, anyone? Freeze-drying is a technique that can help to provide food for astronauts. But it also has other applications nearer home. Freeze-drying is like suspend
2、ed animation for food; you can store a freeze-dried meal for years, and then, when youre finally ready to eat it, you can completely revitalise it with a little hot water. Even after several years, the original foodstuff will be virtually unchanged. The technique basically involves completely removi
3、ng the water from some material, such as food, while leaving the rest of the material virtually intact. The main reason for doing this is either to preserve the food or to reduce its weight. Removing the water from food keeps it from spoiling, because the microorganisms such as bacteria that cause s
4、poiling cannot survive without it. Similarly, the enzymes which occur naturally in food cannot cause ripening without water, so removing water from food will also stop the ripening process. Freeze-drying significantly reduces the total weight of the food because most food is largely made up of water
5、; for example, many fruits are more than 80-90% water. Removing this makes the food much lighter and therefore makes transportation less difficult. The military and camping-supply companies freeze-dry foods to make them easier for an individual to carry and NASA has also freeze-dried foods for the c
6、ramped quarters on board spacecraft. The process is also used to preserve other sorts of material, such as pharmaceuticals. Chemists can greatly extend pharmaceutical shelf life by freeze-drying the material and storing it in a container free of oxygen and water. Similarly, research scientists may u
7、se freeze-drying to preserve biological samples for long periods of time. Even valuable manuscripts that had been water damaged have been saved by using this process. Freeze-drying is different from simple drying because it is able to remove almost all the water from materials, whereas simple drying
8、 techniques can only remove 90-95%. This means that the damage caused by bacteria and enzymes can virtually be stopped, rather than just slowed down. In addition, the composition and structure of the material is not significantly changed, so materials can be revitalised without compromising the qual
9、ity of the original. This is possible because in freeze-drying, solid water ice is converted directly into water vapour, missing out the liquid phase entirely. This is called sublimation, the shift from a solid directly into a gas. Just like evaporation, sublimation occurs when a molecule gains enou
10、gh energy to break free from the molecules around it. Water will sublime from a solid(ice)to a gas(vapour)when the molecules have enough energy to break free but the conditions arent right for a liquid to form. These conditions are determined by heat and atmospheric pressure. When the temperature is
11、 above freezing point, so that ice can thaw, but the atmospheric pressure is too low for a liquid to form(below 0.06 atmospheres(ATM)then it becomes a gas. This is the principle on which a freeze-drying machine is based. The material to be preserved is placed in a freeze-drying chamber which is conn
12、ected to a freezing coil and refrigerator compressor. When the chamber is sealed the compressor lowers the temperature inside it. The material is frozen solid, which separates the water from everything around it on a molecular level, even though the water is still present. Next, a vacuum pump forces
13、 air out of the chamber, lowering the atmospheric pressure below to 0.06 ATM. The heating units apply a small amount of heat to the shelves in the chamber, causing the ice to change phase. Since the pressure in the chamber is so low, the ice turns directly into water vapour, which leaves the freeze-
14、drying chamber, and flows past the freezing coil. The water vapour condenses onto the freezing coil in the form of solid ice, in the same way that water condenses as frost on a cold day. The process continues for many hours(even days)while the material gradually dries out. This time is necessary to
15、avoid overheating, which might affect the structure of the material. Once it has dried sufficiently, it is sealed in a moisture-free package. As long as the package is secure, the material can sit on a shelf for years and years without degrading, until it is restored to its original form with a litt
16、le hot water. If everything works correctly, the material will go through the entire process almost completely unscathed. In fact, freeze-drying, as a general concept, is not new but has been around for centuries. The ancient Incas of Peru used mountain peaks along the Andes as natural food preserve
17、rs. The extremely cold temperatures and low pressure at those high altitudes prevented food from spoiling in the same basic way as a modern freeze-drying machine and a freezer. Questions 1-5 Complete the notes below. Choose NO MORE THAN THREE WORDS from the passage for each answer. Write your answer
18、s in boxes 1-5 on your answer sheet. Uses of freeze-drying food preservation easy 【 R1】 _of food items long-term storage of 【 R2】 _and biological samples preservation of precious 【 R3】 _ Freeze-drying is based on process of 【 R4】 _ is more efficient than 【 R5】 _ 1 【 R1】 2 【 R2】 3 【 R3】 4 【 R4】 5 【 R
19、5】 5 Label the diagram below.Choose NO MORE THAN TWO WORDS from the passage for each answer.Write your answers in boxes 6-9 on your answer sheet. 9 Complete the summary below. Choose NO MORE THAN THREE WORDS AND/OR A NUMBER from the passage for each answer. Write your answers in boxes 10-13 on your
20、answer sheet. Freeze-drying prevents food from going bad by stopping the activity of microorganisms or 【 R10】 _.Its advantages are that the food tastes and feels the same as the original because both the 【 R11】 _and _are preserved. The process is carried out slowly in order to ensure that 【 R12】 _do
21、es not take place. The people of one ancient mountain civilisation were able to use this method of food preservation because the conditions needed were present at 【 R13】 _. 10 【 R10】 11 【 R11】 12 【 R12】 13 【 R13】 13 You should spend about 20 minutes on Questions 14-27, which are based on Reading Pas
22、sage 2 below. THE WILD SIDE OF TOWN The countryside is no longer the place to see wildlife, according to Chris Barnes, These days you are more likely to find impressive numbers of skylarks, dragonflies and toads in your own back garden. The past half century has seen an interesting reversal in the f
23、ortunes of much of Britains wildlife. Whilst the rural countryside has become poorer and poorer, wildlife habitat in towns has burgeoned. Now, if you want to hear a deafening dawn chorus of birds or familiarise yourself with foxes, you can head for the urban forest. Whilst species that depend on wid
24、e open spaces such as the hare, the eagle and the red deer may still be restricted to remote rural landscapes, many of our wild plants and animals find the urban ecosystem ideal. This really should be no surprise, since it is the fragmentation and agrochemical pollution in the farming lowlands that
25、has led to the catastrophic decline of so many species. By contrast, most urban open spaces have escaped the worst of the pesticide revolution, and they are an intimate mosaic of interconnected habitats. Over the years, the cutting down of hedgerows on farmland has contributed to habitat isolation a
26、nd species loss. In towns, the tangle of canals, railway embankments, road verges and boundary he4ges lace the landscape together, providing first-class ecological corridors for species such as hedgehogs, kingfishers and dragonflies. Urban parks and formal recreation grounds are valuable for some sp
27、ecies, and many of them are increasingly managed with wildlife in mind. But in many places their significance is eclipsed by the huge legacy of post-industrial land demolished factories, waste tips, quarries, redundant railway yards and other so-called brownfield sites. In Merseyside, South Yorkshir
28、e and the West Midlands, much of this has been spectacularly colonised with birch and willow woodland, herb-rich grassland and shallow wetlands. As a consequence, there are song birds and predators in abundance over these once-industrial landscapes. There are fifteen million domestic gardens in the
29、UK, and whilst some are still managed as lifeless chemical war zones, most benefit the local wildlife, either through benign neglect or positive encouragement. Those that do best tend to be woodland species, and the garden lawns and flower borders, climber-covered fences, shrubberies and fruit trees
30、 are a plausible alternative. Indeed, in some respects gardens are rather better than the real thing, especially with exotic flowers extending the nectar season. Birdfeeders can also supplement the natural seed supply, and only the millions of domestic cats may spoil the scene. As Britains gardeners
31、 have embraced the idea of gardening with nature, wildlifes response has been spectacular. Between 1990 and the year 2000, the number of different bird species seen at artificial feeders in gardens increased from 17 to an amazing 81. The BUGS project(Biodiversity in Urban Gardens in Sheffield)calcul
32、ates that there are 25,000 garden ponds and 100,000 nest boxes in that one city alone. We are at last acknowledging that the wildlife habitat in towns provides a valuable life support system. The canopy of the urban forest is filtering air pollution, and intercepting rainstorms, allowing the water t
33、o drip more gradually to the ground. Sustainable urban drainage relies on ponds and wetlands to contain storm water runoff, thus reducing the risk of flooding, whilst reed beds and other wetland wildlife communities also help to clean up the water. We now have scientific proof that contact with wild
34、life close to home can help to reduce stress and anger. Hospital patients with a view of natural green space make a more rapid recovery and suffer less pain. Traditionally, nature conservation in the UK has been seen as marginal and largely rural. Now we are beginning to place it at the heart of urb
35、an environmental and economic policy. There are now dozens of schemes to create new habitats and restore old ones in and around our big cities. Biodiversity is big in parts of London, thanks to schemes such as the London Wetland Centre in the south west of the city. This is a unique scheme mastermin
36、ded by the Wildfowl and Wetlands Trust to create a wildlife reserve out of a redundant Victorian reservoir. Within five years of its creation the Centre has been hailed as one of the top sites for nature in England and made a Site of Special Scientific Interest. It consists of a 105-acre wetland sit
37、e, which is made up of different wetland habitats of shallow, open water and grazing marsh. The site attracts more than 104 species of bird, including nationally important rarities like the bittern. We need to remember that if we work with wildlife, then wildlife will work for us and this is the ver
38、y essence of sustainable development. Questions 14-19 Do the following statements agree with the information given in Reading Passage 2? In boxes 14-19 on your answer sheet, write TRUE if the statement agrees with the information FALSE if the statement contradicts the information NOT GIVEN if there
39、is no information on this 14 There is now more wildlife in UK cities than in the countryside. （ A） TRUE （ B） FALSE （ C） NOT GIVEN 15 Rural wildlife has been reduced by the use of pesticides on farms. （ A） TRUE （ B） FALSE （ C） NOT GIVEN 16 In the past, hedges on farms used to link up different habita
40、ts. （ A） TRUE （ B） FALSE （ C） NOT GIVEN 17 New urban environments are planned to provide ecological corridors for wildlife. （ A） TRUE （ B） FALSE （ C） NOT GIVEN 18 Public parks and gardens are being expanded to encourage wildlife. （ A） TRUE （ B） FALSE （ C） NOT GIVEN 19 Old industrial wastelands have
41、damaged wildlife habitats in urban areas. （ A） TRUE （ B） FALSE （ C） NOT GIVEN 20 Which type of wildlife benefits most from urban gardens? 21 What type of garden plants can benefit birds and insects? 22 What represents a threat to wildlife in urban gardens? 23 At the last count, how many species of b
42、ird were spotted in urban gardens? 23 Choose THREE letters A-G. Write your answers in boxes 24-26 on your answer sheet. In which THREE ways can wildlife habitats benefit people living in urban areas? A They can make the cities greener. B They can improve the climate. C They can promote human well-be
43、ing. D They can extend the flowering season. E They can absorb excess water. F They can attract wildlife. G They can help clean the urban atmosphere. 27 The writer believes that sustainable development is dependent on （ A） urban economic policy. （ B） large restoration schemes. （ C） active nature con
44、servation. （ D） government projects. 27 Running on empty A revolutionary new theory in sports physiology. A For almost a century, scientists have presumed, not unreasonably, that fatigue or exhaustion in athletes originates in the muscles. Precise explanations have varied, but all have been based on
45、 the limitations theory. In other words, muscles tire because they hit a physical limit: they either run out of fuel or oxygen or they drown in toxic by-products. B In the past few years, however, Timothy Noakes and Alan St Clair Gibson from the University of Cape Town, South Africa, have examined t
46、his standard theory. The deeper they dig, the more convinced they have become that physical fatigue simply isnt the same as a car running out of petrol. Fatigue, they argue, is caused not by distress signals springing from overtaxed muscles, but is an emotional response which begins in the brain. Th
47、e essence of their new theory is that the brain, using a mix of physiological, subconscious and conscious cues, paces the muscles to keep them well back from the brink of exhaustion. When the brain decides its time to quit, it creates the distressing sensations we interpret as unbearable muscle fati
48、gue. This central governor theory remains controversial, but it does explain many puzzling aspects of athletic performance. C A recent discovery that Noakes calls the lactic acid paradox made him start researching this area seriously. Lactic acid is a by-product of exercise, and its accumulation is
49、often cited as a cause of fatigue. But when research subjects exercise in conditions simulating high altitude, they become fatigued even though lactic acid levels remain low. Nor has the oxygen content of their blood fallen too low for them to keep going. Obviously, Noakes deduced, something else was making them tire before they hit either of these physiological limits. D Probing further, Noakes conducted an experiment with seven cyclists who had sensors taped to their legs to measure the nerve impu
