大学英语四级考试及答案模拟题三范文.docx

1、大学英语四级考试及答案模拟题三范文模拟题三Part Writing (30 minutes)Directions: For this part, you are allowed 30 minutes to write a composition on the topic Dormitory Life . You should write at least 120 words following the outline given below in Chinese:Dormitory Life1. 大学宿舍的集体生活是全新的体验。2. 宿舍生活与在家生活的不同之处。3. 宿舍生活利与弊。Part

2、 II Reading Comprehension (Skimming and Scanning)Directions: In this part, you will have 15 minutes to go over the passage quickly and answer the questions on Answer sheet1.Testing TimesResearchers are working on ways to reduce the need for animal experiments, but new laws may increase the number of

3、 experiments needed. The current situationIn an ideal world, people would not perform experiments on animals. For the people, they are expensive. For the animals, they are stressful and often painful.That ideal world, sadly, is still some way away. People need new drugs and vaccines. They want prote

4、ction from the toxicity of chemicals. The search for basic scientific answers goes on. Indeed, the European Commission is forging ahead with proposals that will increase the number of animal experiments carried out in the European Union, by requiring toxicity tests on every chemical approved for use

5、 within the unions borders in the past 25 years.Already, the commission has identified 140,000 chemicals that have not yet been tested. It wants 30,000 of these to be examined right away, and plans to spend between 4 billion 8 billion ($5 billion10 billion) doing so. The number of animals used for t

6、oxicity testing in Europe will thus, experts reckon, quintuple (翻五倍) from just over lm a year to about 5m, unless they are saved by some dramatic advances in non-animal testing technology. At the moment, roughly 10% of European animal tests are for general toxicity, 35% for basic research, 45% for d

7、rugs and vaccines, and the remaining 10% a variety of uses such as diagnosing diseases.Animal experimentation will therefore be around for some time yet. But the search for substitutes continues, and last weekend the Middle European Society for Alternative Methods to Animal Testing met in Linz, Aust

8、ria, to review progress.A good place to start finding alternatives for toxicity tests is the liver-the organ responsible for breaking toxic chemicals down into safer molecules that can then be excreted. Two firms, one large and one small, told the meeting how they were using human liver cells remove

9、d incidentally during surgery to test various substances for long-term toxic effects.One way out of the problemPrimeCyte, the small firm, grows its cells in cultures over a few weeks and doses them regularly with the substance under investigation. The characteristics of the cells are carefully monit

10、ored, to look for changes in their microanatomy.Pfizer, the big firm, also doses its cultures regularly, but rather than studying individual cells in detail, it counts cell numbers. If the number of cells in a culture changes after a sample is added, that suggests the chemical in question is bad for

11、 the liver.In principle, these techniques could be applied to any chemical. In practice, drugs (and, in the case of PrimeCyte, food supplements) are top of the list. But that might change if the commission has its way: those 140,000 screenings look like a lucrative market, although nobody knows whet

12、her the new tests will be ready for use by 2009, when the commission proposes that testing should start.Other tissues, too, can be tested independently of animals. Epithelix, a small firm in Geneva, has developed an artificial version of the lining of the lungs. According to Huang Song, one of Epith

13、elixs researchers, the firms cultured cells have similar microanatomy to those found in natural lung linings, and respond in the same way to various chemical messengers. Dr. Huang says that they could be used in long-term toxicity tests of airborne chemicals and could also help identify treatments f

14、or lung diseases.The immune system can be mimicked and tested, too. ProBioGen, a company based in Berlin, is developing an artificial human lymph node (淋巴结) which, it reckons, could have prevented the neardisastrous consequences of a drag trial held in Britain three months ago, in which (despite the

15、 drag having passed animal tests) six men suffered multiple organ failure and nearly died. The drug the men were given made their immune systems hyperactive. Such a response would, the firms scientists reckon, nave teen identified by their lymph node, which is made from cells that provoke the immune

16、 system into a response. ProBioGens lymph node could thus work better than animal testing. A second alternativeAnother way of cutting the number of animal experiments would be to change the way that vaccines are tested, according to Coenraad Hendriksen of the Netherlands Vaccine Institute. At the mo

17、ment, all batches of vaccine are subject to the same battery of tests. Dr. Hendriksen argues that this is over-rigorous. When new vaccine cultures are made, belt-and-braces tests obviously need to be applied. But if a batch of vaccine is derived from an existing culture, he suggests that it need be

18、tested only to make sure it is identical to the batch from which it is derived. That would require fewer test animals.All this suggests that though there is still some way to go before drugs, vaccines and other substances can be tested routinely on cells rather than live animals, useful progress is

19、being made. What is harder to see is how the use of animals might be banished from fundamental research. Weighing the balanceIn basic scientific research, where the object is to understand how, say, the brain works rather than to develop a drug to treat brain disease, the whole animal is often neces

20、sarily the object of study. Indeed, in some cases, scientific advances are making animal tests more valuable, rather than less. Geneticmodification techniques mean that mice and rats can be remodelled to make them exhibit illnesses that they would not normally suffer from. Also, genes for human prot

21、eins can be added to them, so that animal tests will more closely mimic human responses. This offers the opportunity to understand human diseases better, and to screen treatments before human trials begin. However, the very creation of these mutants (突变异种) counts as an animal experiment in its own r

22、ight, so the number of experiments is increasing once again.What is bad news for rodents, though, could be good news for primates. Apes and monkeys belong to the same group of mammals as humans, and are thus seen as the best subjects for certain sorts of experiment. To the extent that rodents can be

23、 humanised, the number of primate experiments might be reduced.Some people, of course, would like to see them eliminated altogether, regardless of the effect on useful research. On June 6th the British Union for the Abolition of Vivisection, an animal-rights group, called for the use of primates in

24、research to be banned. For great apes, this has already happened. Britain, Austria, the Netherlands, New Zealand and Sweden have ended experiments on chimpanzees, gorillas, bonobos and orang-utans. Experiments on monkeys, though, are still permitted. And some countries have not banned experiments on

25、 apes. In America, for example, about 1,000 chimpanzees a year are used in research.This is a difficult area. Great apes are mans closest relatives, having parted company from the human family tree only a few million years ago. Hence it can be (and is) argued that they are indispensable for certain

26、sorts of research. On the other hand, a recent study by Andrew Knight and his colleagues at Animal Consultants International, an animal-advocacy group, casts doubt on the claim that apes are used only for work of vital importance to humanity. Important papers tend to get cited as references in subse

27、quent studies, so Mr. Knight looked into the number of citations received by 749 scientific papers published as a result of invasive experiments on captive chimpanzees. Half had received not a single citation up to ten years after their original publication.That is damning. Animal experiments are ne

28、eded for the advance of medical science, not to mention peoplessafety. But if scientists are to keep the sympathy of the public, they need to do better than that.1. The passage summarizes harmful effects of animal experiment. However, as animal experiment is indispensable in a number of areas, it mi

29、ght not be stopped or replaced by other alternatives.2. Animal experiments are needed in research to find new drugs and vaccines, and to find ways of protection from the toxicity of chemicals.3. It is predicted by experts that the number of animals used for toxicity testing in Europe will quintuple

30、due to a plan to have a large variety of chemical tested.4. People are trying to find alternatives to animal testing, and they started with liver.5. PrimeCyte and Pfizer began to find alternatives to animal testing because they were advocates of animal protection.6. It is found that tissues from liv

31、er, lung, and immune system can all be tested independently of animals.7. Although there is more than one alternative to animal experiment, there is still concern over how to eliminate animal testing in fundamental research.8. In basic scientific research, the object is to understand how, say, the b

32、rain works rather than to develop a drug to _ brain disease.9. Indeed, in some cases, scientific advances are making animal tests _10. Recently, an animal-advocacy group casts doubt on the scientists claim that apes are used only for _Part IV Reading Comprehension (Reading in Depth)Section ADirections: In this section, there is a passage with ten blanks. You are required to select one word for each blank from a list of choices given in a word bank following the passage. Read the passage through carefully before makingyour choices. Each choice in the bank is identi