《2022年大学英语四级考试模拟试卷及答案(6).docx》由会员分享，可在线阅读，更多相关《2022年大学英语四级考试模拟试卷及答案(6).docx（9页珍藏版）》请在金锄头文库上搜索。
1、 2022大学英语四级考试模拟试卷及答案(6)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 II Reading Comprehensi
2、on (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 experiments needed. Th
3、e 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 protection from the toxicity
4、 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 within the union”s bor
5、ders 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 toxicity testing in Eur
6、ope 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 drugs and vaccines, and
7、 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, Austria, to review progres
8、s.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 removed incidentally during
9、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 monitored, to look for chan
10、ges 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 the liver.In principl
11、e, 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 whether the new tests will
12、 be ready for use by 2022, 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 Epithelix”s researchers, th
13、e firm”s 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 for lung diseases.The
14、 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 drag having passed
15、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 firm”s scientists reckon, nave teen identified by their lymph node, which is made from cells that provoke the immune system into a resp
16、onse. ProBioGen”s 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 moment, all batches of vaccine are subject to the same battery of
