大学英语四级56及答案解析.doc

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1、大学英语四级 56 及答案解析(总分：746.58，做题时间：130 分钟)一、Writing (30 minutes)(总题数：1，分数：30.00)1.For this part, you are allowed 30 minutes to write an essay entitled On Conserving Energy. You should write at least 120 words following the outline given below in Chinese: 1. 能源短缺问题已非常严重； 2. 可以采取节能措施解决能源短缺问题； 3. 你的看法。 （分数

2、：30.00）_二、Reading Comprehensio(总题数：1，分数：71.00)A Mystery in the Lunchbox Hungry? Sit down. Were having catfish, corn on the cob, baked potatoes and fresh tomatoes. This might turn out to be the most nutritious meal of your life. It might even be the best-tasting dinner you ever had. On the other hand

3、, it might induce an allergic (过敏性的) reaction even though you are not allergic to any of these foods. Different Opinions about Biotechnology (生物工程) Products Last weeks announcement that the U.S. federal government would impose no special regulations on bioengineered foods, in effect permitting them

4、to be marketed exactly like natures own, proclaims a potentially vast change in our food supply. “We will not compromise safety one bit,“ Vice President Dan Quayle told the press. “And consumers will enjoy better, healthier food products at lower prices.“ Many specialists in biotechnology agree in f

5、act, they see consumers around the world benefiting from a new, genetically-engineered green revolution but critics are urging the government to move ahead more cautiously. “We should have learned from the history of regulating pesticides (杀虫剂) that we never knew the long-term consequences until it

6、was too late,“ says Ellen Haas, executive director of Public Voice for Food and Healthy Policy, a Washington D.C.-based advocacy group. The Food and Drug Administration maintains that most bioengineered foods present no special safety issues. “Were saying this is just another plant-breeding techniqu

7、e,“ says Eric Flamm, deputy director of the FDAs Office of Biotechnology. How Does Recombination of DNA Work? Heres how bioengineering works: all cells contain DNA, the long molecule (分子) shaped like a double helix (螺旋). A gene is a swatch (样本) of DNA that controls a certain characteristic of the or

8、ganism. In the 1970s scientists discovered they could clip off a gene-length swatch from a DNA molecule, and later they learned to affix (固定) it to a different DNA molecule a cut-and-paste job that became known as gene splicing and results in whats called recombinant DNA. Immediately, visions of car

9、rots with the flavor of peanut butter began dancing in the imaginations of scientists and food writers alike. But most current experiments are less exotic (异乎寻常的). In many ways the new technology differs little from traditional crossbreeding. One Product of Bioengineered Technology The first example

10、 of recombinant DNA in a form suitable for lunch makes its debut (首次露面) next summer: the Flavr Savr tomato. Scientists at Calgene, Inc., a biotech company based in Davis, California, isolated the gene in the tomato that triggers the enzyme (酶) responsible for rotting and rendered it inactive. Rather

11、 man having to be picked hard and green for easy shipping, the tomatoes stay on the vine about five days longer than usual. They can be shipped* without refrigeration, which also helps retain flavor, and theyll resist rotting for more man three weeks, twice as long as their conventionally grown cous

12、ins. They arent perfect: like other supermarket tomatoes theyre grown with pesticides, they may be waxed, and they still lack the last three to five days of vine-ripening that homegrown tomatoes enjoy. Sampled at Calgenes headquarters, the Flavr Savr tasted fine; whether consumers still find it wort

13、h a dollar more per pound remains to be seen. Developing Pest Resistant Plant Several companies are hard at work on plants that will repel (抵制) pests (害虫). Monsanto, a St. Louis, Missouri, chemical company, expects to put many such products on the market before the end of the decade. The weapon of c

14、hoice is Bacillus thuringiensis, or BT, a soil-dwelling bacterium (细菌) that creates a protein crystal that is toxic to certain insects but harmless digested by humans. BT has been used for 30 years as an organic pesticide. Scientists can transfer the gene for the toxin into plant cells, and the new

15、plants will produce their own insecticides. Like traditional insecticides, however, these may simply spur the creation of new, more resistant pests. According to Belknap, the solution will be to splice several toxins into a given plant, thus lessening the potential for insects to develop resistance

16、(or inviting the birth of some pretty amazing insects). One Member of the Herbicide (除草剂) Family, and Its Problems Monsanto is also developing herbicide-resistant plants, specifically Roundup-resistant plants. Roundup is one of Monsantos most lucrative (获利的) products, a herbicide with sales of a bil

17、lion dollars a year. It has been recognized as noncarcinogenic (非致癌的) by the Environmental Protection Agency, though its toxic to fish. Roundup is used as a weed-killer, but it will kill everything else it touches in the field, so farmers have had to apply it carefully. Now, however, Monsanto can is

18、olate the enzyme in, say, corn, that is fatally vulnerable to Roundup. A corn plant engineered to have twice as much of that enzyme can lose a chunk of it to Roundup and still survive. Critics charge that this technology simply invites fanners to use more Roundup. Good News for the Business but Cons

19、umers Are Entitled to Know What They Are Eating Its not surprising that biotechnology companies were delighted by the FDAs green light. Environmentalists and other consumer advocates dont claim the new foods are unsafe by definition, but they do call for tougher scrutiny (监督) than the FDA believes i

20、s necessary. “The regulations do a lot more to protect the industry than they do to protect the American consumers, “says Rebecca Goldburg, a senior scientist at the Environmental Defense Fund, an advocacy group. “The public has a right to know whats in its food.“ Its Up to the Biotechnology Industr

21、y, not FDA Goldbury and other critics are especially concerned about potential allergens that may be hiding in new products an orange touched up with a gene from a cherry, for instance. The FDA requires no special testing or labeling unless the new food is substantially different from its traditiona

22、l version. A new food containing a “common allergen“ would also have to be labeled, but as examples of common allergens the FDA suggests only eggs, milk, fish, shellfish, tree nuts, wheat and other legumes. The truth is, almost any food is an allergen (过敏源) to someone. According to the FDA, its up t

23、o the biotechnology industry to police itself on potential allergens. “If you move a gene, you have to prove it not allergenic or you will have to label it,“ says Flamm. There Are Better Ways to Produce Food than Using Biotechnological Methods Other critics are uneasy about making such dramatic chan

24、ges with such speed. “We ought to be testing these changes in large populations over large periods of time,“ says Greg Drescher, a director of Old-ways Preservation whether consumers still find it worth a dollar more per pound remains to be seen. Developing Pest Resistant Plant Several companies are

25、 hard at work on plants that will repel (抵制) pests (害虫). Monsanto, a St. Louis, Missouri, chemical company, expects to put many such products on the market before the end of the decade. The weapon of choice is Bacillus thuringiensis, or BT, a soil-dwelling bacterium (细菌) that creates a protein cryst

26、al that is toxic to certain insects but harmless digested by humans. BT has been used for 30 years as an organic pesticide. Scientists can transfer the gene for the toxin into plant cells, and the new plants will produce their own insecticides. Like traditional insecticides, however, these may simpl

27、y spur the creation of new, more resistant pests. According to Belknap, the solution will be to splice several toxins into a given plant, thus lessening the potential for insects to develop resistance (or inviting the birth of some pretty amazing insects). One Member of the Herbicide (除草剂) Family, a

28、nd Its Problems Monsanto is also developing herbicide-resistant plants, specifically Roundup-resistant plants. Roundup is one of Monsantos most lucrative (获利的) products, a herbicide with sales of a billion dollars a year. It has been recognized as noncarcinogenic (非致癌的) by the Environmental Protecti

29、on Agency, though its toxic to fish. Roundup is used as a weed-killer, but it will kill everything else it touches in the field, so farmers have had to apply it carefully. Now, however, Monsanto can isolate the enzyme in, say, corn, that is fatally vulnerable to Roundup. A corn plant engineered to h

30、ave twice as much of that enzyme can lose a chunk of it to Roundup and still survive. Critics charge that this technology simply invites fanners to use more Roundup. Good News for the Business but Consumers Are Entitled to Know What They Are Eating Its not surprising that biotechnology companies wer

31、e delighted by the FDAs green light. Environmentalists and other consumer advocates dont claim the new foods are unsafe by definition, but they do call for tougher scrutiny (监督) than the FDA believes is necessary. “The regulations do a lot more to protect the industry than they do to protect the Ame

32、rican consumers, “says Rebecca Goldburg, a senior scientist at the Environmental Defense Fund, an advocacy group. “The public has a right to know whats in its food.“ Its Up to the Biotechnology Industry, not FDA Goldbury and other critics are especially concerned about potential allergens that may b

33、e hiding in new products an orange touched up with a gene from a cherry, for instance. The FDA requires no special testing or labeling unless the new food is substantially different from its traditional version. A new food containing a “common allergen“ would also have to be labeled, but as examples

34、 of common allergens the FDA suggests only eggs, milk, fish, shellfish, tree nuts, wheat and other legumes. The truth is, almost any food is an allergen (过敏源) to someone. According to the FDA, its up to the biotechnology industry to police itself on potential allergens. “If you move a gene, you have

35、 to prove it not allergenic or you will have to label it,“ says Flamm. There Are Better Ways to Produce Food than Using Biotechnological Methods Other critics are uneasy about making such dramatic changes with such speed. “We ought to be testing these changes in large populations over large periods

36、of time,“ says Greg Drescher, a director of Old-ways Preservation & Exchange Trust, a Boston-based think-tank for food issues. He also questions how useful the new foods really are. “We dont need to play sorcerers (魔法师) apprentice (学徒) with agriculture,“ he says. “We know how to produce good-tasting

37、 food in this country. There are much better ways to eat healthfully than a food supply based on techno-foods.“ Jeremy Rifkin, the activist who has been fighting biotechnology for years, promises lawsuits and a massive publicity campaigns, and he thinks the public will be on his side. “If people don

38、t want foods pumped full of hormones (激素) and antibiotics (抗生素), they are never going to go along with genetically-engineered foods,“ he says. At the very least, these critics may persuade the FDA to require more labeling of the new foods. （分数：71.00）(1).The general public so far has responded to bio

39、engineered food positively.（分数：7.10）A.YB.NC.NG 解析：通读全文，我们可以看出美国食品与药品管理局(FDA)对生物工程食品予以放行，不加以限制，环保主义者和批评家们则对这些新食品持怀疑或否定的态度，而并未提及公众意见，故正确答案是此说法没有被提及。(2).Carrots with the flavor of peanut butter are available in ordinary supermarkets.（分数：7.10）A.YB.N C.NG解析：根据文章第三段第六至七行，我们可以看出基因重组技术一旦成功，花生酱口味的胡萝卜的影像便开始跳跃

40、在科学家们的脑海中。但这只是他们的大胆设想，还没有付诸实验，因此可推断出这种食品已上市的说法是错误的。(3).Roundup is a very effective pesticide.（分数：7.10）A.YB.N C.NG解析：文章第六段提到 Roundup 是 Monsanto 公司最赚钱的产品，但本段第五行表明它是作为一种除草剂被使用的，而不是杀虫剂，故此说法是错误的。(4).Biotechnology methods are used to produce tomatoes that soften later than usual.（分数：7.10）A.Y B.NC.NG解析：根据第

41、四段第四行“Rather than having to be picked hard and green for easy shipping，the tomatoes stay on the vine about five days longer than usual，”可推测此说法是正确的。(5).Though BT is toxic to fish, it is harmless to human.（分数：7.10）A.YB.N C.NG解析：根据第五段第三至五行，BT 是一种存在于土壤中的细菌，能够分泌出对某些昆虫有毒的蛋白晶体，但是进入人体时却不会造成危害。并未提到它对鱼类有害，故此说

42、法是错误的。(6).According to the regulations of FDA, if the newly-produced orange had no vitamin C, it would have to be labeled.（分数：7.10）A.Y B.NC.NG解析：根据第八段“The FDA requires no special testing or labeling unless the new food is substantially different from its traditional version，” 可知美国食品与药品管理局规定，生物工程食品不必

43、经过特殊检验或做出标识，除非与其传统形态性质完全不同。由此可见，如果转基因橙子不含维生素 C，那么就需要对其做出标识，因为它与传统橙子有着本质的不同。(7).Biotechnology methods applied in food industry are more profitable than similar methods applied in medical science.（分数：7.10）A.YB.NC.NG 解析：通读全文，我们会发现作者只谈到生物技术应用于食品工业的原理、相关产品的优缺点以及政府和业内人士的观点，并没有提到类似技术在医疗领域的应用和效果，故正确答案是此说法没有

44、被提及。(8).If scientists could transfer the gene of BT into plant cells successfully, the new plants will_.（分数：7.10）_正确答案：(produce their own insecticides)解析：根据文章第五段第六行“Scientists can transfer the gene for the toxin into plant cells，and the new plants will produce their own insecticides”可知正确答案应是 produce

45、 their own insecticides(9).When the newly-produced tomato is sold on the market, customers are supposed to pay_.（分数：7.10）_正确答案：(a dollar more per pound)解析：从第四段最后一句话“Sampled at Calgenes headquarters，the Flavr Savr tasted fine；whether consumers still find it worth a dollar more per pound remains to be

46、 seen”可看出正确答案应是 a dollar more per pound(10).At present, there is no special testing or labeling required unless the new food is substantially different from_.（分数：7.10）_正确答案：(its traditional version)解析：根据第八段“The FDA requires no special testing or labeling unless the new food is substantially differen

47、t from its traditional version”正确答案应是 its traditional version三、Listening Comprehens(总题数：1，分数：15.00)A.She takes it as a kind of exercise. B.She wants to save money.C.She loves doing anything that is new.D.Her office isnt very far.解析：M: Hi, Susan. I hear that you walk all the way to the office these d

48、ays? W: Yes. I have found great pleasure in walking. Thats the type of exercise I enjoy very much. Q: Why does the woman walk all the way to the office? A.It is difficult to identify.B.It has been misplaced. C.It is missing.D.It has been borrowed by someone.解析：W: Jack, I cant find Volume 10. Could you check for me who borrowed it? M: Here it i