1、大学英语四级-297 及答案解析(总分：100.00，做题时间：90 分钟)一、Reading Comprehensio(总题数：0，分数：0.00)二、Section A(总题数：1，分数：30.00)For an increasing number of students at American universities, old is suddenly in. The reason is 1 : the graying of America means jobs. Coupled with the aging of the baby-boom generation, a longer l
2、ife 2 means that the nation“s elderly population is 3 to expand 4 over the next 50 years. By 2050, 25 percent of all Americans will be older than 65, up from 14 percent in 1995. The change 5 profound questions for government and society, of course. But it also creates career opportunities in medicin
3、e and health professions, and in law and business as well. “In addition to the doctors, we“re going to need more sociologists, biologists, urban planners and specialized lawyers,“ says Professor Edward Schneider of the University of Southern California“s (USC. School of Gerontology (老年学). Lawyers ca
4、n 6 in “elder law“, which 7 everything from trusts and estates to nursing-home 8 and age discrimination (歧视). Businessmen see huge opportunities in the elder market because the baby boomers, 74 million, are likely to be the wealthiest group of 9 in human history. “Any student who combines an expert
5、knowledge in gerontology with, says that, an MBA or law degree will have a license to print money,“ one professor says. Margarite Santos is a 21-year-old senior at USC. She began college as a biology major but found she was “really bored with bacteria“. So she took a class in gerontology and discove
6、red that she liked it. She says, “I did volunteer work in retirement homes and it was very 10 .“ A. covers B. obtains C. span D. specialize E. poses F. longevity G. satisfying H. retirees I. abuse J. easy K. significantly L. specified M. obvious N. slightly O. bound（分数：30.00）三、Section B(总题数：1，分数：35.
7、00)Jaguars Don“t Live Here AnymoreA Earlier this month, the United States Fish and Wildlife Service announced it would appoint “critical habitat“ for the endangered jaguar. Jaguarsthe world“s third-largest wild cats, weighing up to 250 pounds, with distinctive black rosettes on their furare a separa
8、te species from the smaller, tawny mountain lions, which still roam large areas of the American West in the United States. The United States is taking the first step toward mandating (批准) a jaguar recovery plan. This is a policy reversal and, on the surface, it may appear to be a victory for the con
9、servation community and for jaguars, the largest wild cats in the Western Hemisphere. B But as someone who has studied jaguars for nearly three decades, I can tell you it is nothing less than a slap in the face to good science. What“s more, by changing the rules for animal preservation, it stands to
10、 weaken the Endangered Species Act. C The debate on what to do about jaguars started in 1997, when, at the urging of many biologists (including me), the Fish and Wildlife Service put the jaguar on the United States endangered species list, because there had been occasional sightings of the cats cros
11、sing north over the United States-Mexico border. At the same time, however, the agency ruled that it would not be “prudent“ to declare that the jaguar has critical habitata geographic area containing features that the species needs to survivein the United States. Determining an endangered species“ c
12、ritical habitat is a first step toward developing a plan for helping that species recover. D The 1997 decision not to determine critical habitat for the jaguar was the right one, because even though they cross the border from time to time, jaguars don“t occupy any territory in our country and that p
13、robably means the environment here is no longer ideal for them. E In prehistoric times, these beautiful cats inhabited significant areas of the western United States, but in the past 100 years, there have been few, if any, resident breeding populations here. The last time a female jaguar with a cub
14、was sighted in this country in the early 1900s. F Two well-intentioned conservation advocacy groups, the Center for Biological Diversity and Defenders of Wildlife, sued the Fish and Wildlife Service to change its ruling. Thus in 2006, the agency reassessed the situation and again determined that no
15、areas in the United States met the definition of critical habitat for the jaguar. Despite occasional sightings, mostly within 40 miles of the Mexican border, there were still no data to indicate jaguars had taken up residence inside the United States. G Alter this second ruling was made, an Arizona
16、rancher (牧场主), with support from the state Department of Game and Fish, set infrared-camera (红外摄像机) traps to collect more data, and essentially confirmed the Fish and Wildlife Service“s findings. The cameras did capture transient jaguars, including one male jaguar, nick named Macho, who roamed the A
17、rizona borderlands for more than a decade. But Macho, now dead, might have been the sole resident American jaguar, and his extensive travels indicated he was not having an easy time surviving in this dry, rugged region. H Despite the continued evidence, the two conservation advocacy groups continued
18、 to sue the government. Apparently, they want jaguars to repopulate the United States even if jaguars don“t want to. Last March, a federal district judge in Arizona ordered the Fish and Wildlife Service to revisit its 2006 determination on critical habitat. I The facts haven“t changed: there is stil
19、l no area in the United States essential to the conservation of the jaguar. But, having asserted this twice already, the service, now under a new president, has bent to the tiresome litigation (诉讼). On Jan. 12, the Fish and Wildlife officials, claimed to have evaluated new scientific information tha
20、t had become available after the July 2006 ruling. They determined that it is now prudent to appoint critical habitat for the jaguar in the United States. J This means that the Fish and Wildlife Service must now also formulate a recovery plan for the jaguar. And since jaguars have not been able to r
21、eestablish themselves naturally over the past century, the government will likely have to go to significant expense to attempt to bring them backespecially if the cats have to be reintroduced. K So why not do everything we can, at whatever cost, to bring jaguars back into the United States? To begin
22、 with, the American Southwest is, at best, marginal habitat for the animals. More important, there are better ways to help jaguars. South of our border, from Mexico to Argentina, thousands of jaguars live and breed in their true critical habitat. Governments and conservation groups are already worki
23、ng hard to conserve jaguar populations and connect them to one another through an initiative called the Jaguar Corridor. L The jaguars that now and then cross into the United States most likely come from the northern in Sonora, Mexico. Rather than demand jaguars return to our country, we should help
24、 Mexico and other jaguar-range countries conserve the animals“ true habitat. M The recent movement by the Fish and Wildlife Service means that the rare federal funds devoted to protecting wild animals will be wasted on efforts that cannot help save jaguars. It also stands to weaken the Endangered Sp
25、ecies Act, because if critical habitat is redefined as any place where a species might ever have existed, and where you or I might want it to exist again, then the door is open for many other senseless efforts to bring back long-lost creatures. N The Fish and Wildlife officials whose job is to prote
26、ct the country“s wild animals which need to grow a stronger backbonestick with their original, correct decision and save their money for more useful preservation work. Otherwise, when funds are needed to preserve all those small, ugly, non-charismatic endangered species at the back of the line, ther
27、e may be no money left.（分数：35.00）(1).It is still a fact that there is no suitable place for jaguars to live safely in the United States.（分数：3.50）(2).The United States Fish and Wildlife Service should be more determined and saving for the conservation work.（分数：3.50）(3).Jaguars were regarded as endang
28、ered species because of their rare appearance at the United States-Mexico border.（分数：3.50）(4).Money was not spent effectively in helping save jaguars in the recent movement by the Fish and Wildlife Service.（分数：3.50）(5).It can be inferred that the United States is not the best choice for jaguars to l
29、ive from the evidence that they don“t settle anywhere here.（分数：3.50）(6).South of the United States“ border, from Mexico to Argentina, is the true critical habitat for jaguars.（分数：3.50）(7).The number of jaguars breeding populations in significant areas of the western United States has decreased in th
30、e past century.（分数：3.50）(8).It is necessary for the government to invest lots of funds in order to help jaguars to reestablish.（分数：3.50）(9).It didn“t indicate that jaguars had settled down in the United States even though they were seen within 40 miles of the Mexican border at times.（分数：3.50）(10).Th
31、e Fish and Wildlife officials were sure enough to appoint critical habitat for the jaguar in the United States.（分数：3.50）四、Section C(总题数：0，分数：0.00)五、Passage One(总题数：1，分数：17.50)It seems like science fiction, but it“s already a reality: milk from cloned cows, and it“s coming to a grocery store near you
32、 unless the federal government decides to intervene. An experimental dairy farm in Wisconsin is producing some of the world“s first milk from a herd of 21 cloned cows, 17 of them from the same original animal, all genetically identical. Infigen, the biotech company that runs the farm, says its cows
33、are normal and healthy, the milk looks and tastes just like any other. The lack of any completed scientific study on the milk“s safety doesn“t stop Infigen“s president, Michael Bishop, from pouring himself a glass. “It“s delicious,“ he said. The Food and Drug Administration (FDA. has asked biotech c
34、ompanies to voluntarily refrain (抑制) from selling animal products derived from clones, but there are no laws in place. The FDA is waiting for the National Academy of Sciences to complete a review of the safety of cloned animal products. The report is expected sometime in January. Infigen has agreed
35、to wait until the federal report comes out before marketing its milk, but it“s mostly a public relations move. Bishop has learned from the widespread public mistrust of genetically engineered foods. Cloned animals are not considered genetically engineered (their DNA has not been modified in any way,
36、 simply copied), and Infigen wants to make sure the public understands the distinction. “We have to be diligent in getting in front of consumer groups. We need to put together the data, go out and tell them about this.“ Groups that monitor genetically engineered foods say they are also concerned abo
37、ut cloned animal products, only because we know so little about their safety. “We don“t know what the genetic ramifications (支流) would be and how it would play out with products from the animals,“ said Joe Mendelson, legal director for the Washington-based Center for Food Safety.（分数：17.50）(1).Which
38、of the following is NOT the feature of cloned cows?（分数：3.50）A.They are of the same origin.B.They are not genetically engineered.C.They are genetically identical.D.They produce milk.(2).When can the milk from cloned cows be sold at grocery stores?（分数：3.50）A.When the federal government stops interveni
39、ng.B.After the cows prove to be normal and healthy.C.When the milk proves to be safe to drink.D.After Infigen“s president drinks the milk himself.(3).Why can“t FAD stop Infigen from selling its milk?（分数：3.50）A.Because Infigen can show their consumers that its milk is normal.B.Because the National Ac
40、ademy of Sciences can prove the safety of cloned animal products.C.Because most people like the milk from cloned cows.D.Because there“s no law to prohibit it from selling the milk.(4).The term “genetically engineered“ (Para. 4) most probably means _.（分数：3.50）A.the DNA has been modifiedB.the DNA has
41、become irregularC.the DNA has been copiedD.the DNA has become abnormal(5).From the passage, we can draw the conclusion that the major problem of cloned animal products is its _.（分数：3.50）A.regularityB.safetyC.normalityD.popularity六、Passage Two(总题数：1，分数：17.50)Can computer reason? Reasoning requires th
42、e individual to take a given set of facts and draw correct conclusions. Unfortunately, errors frequently occur, and we are not talking about simple carelessness as occurs when two numbers are incorrectly added, nor do we mean errors resulting from simple forgetfulness. Rather, we have in mind errors
43、 of a logical naturethose resulting from faulty reasoning. Now, or at least soon, computers will be capable of error-free logical reasoning in a variety of areas. The key to avoiding errors is to use a computer programAURA (Automated Reasoning Assistant)that relies on the recent research in the fiel
44、d of automated theorem proving. AURA solves a program by drawing conclusions from a given set of facts about the problem. The program reaches logical conclusions flawlessly as it uses various types of reasoning and solves almost all problems by using sophisticated techniques to find a contradiction.
45、 One generally starts with a set of assumptions and adds a statement that the goal is unreachable. For example, if the problem is to test a safety system that automatically shuts down a nuclear reactor when instruments indicate a problem, AURA is told that the system will not shut the reactor down u
46、nder those circumstances. If AURA finds a contradiction between the statement and the system“s design assumptions, then this aspect of the reactor“s design has been proved satisfactory. This strategy lets AURA concentrate on the problem at hand and avoid the many fruitless steps required to explore
47、the entire theory underlying the problem. The chief use for AURA at this time is for electronic circuit design validation, but a number of other uses will arise. For example, there already exist “expert systems“ that are special purpose programs designed to automate reasoning in a specific area such
48、 as medical diagnosis. These expert systems continue to improve and have an indefinite life span. Moreover, they can be duplicated for pennies. A human who can expertly predict where to drill for oil is in great demand. A program that can predict equally well would be invaluable and could be duplica
49、ted any number of times. It seems likely that computer programs will reproduce more clever programs and more efficient components. Reasoning programs will also analyze their own progress, learn from their attempts to solve a problem. Reasoning assistants will enable human minds to turn to deeper and more complex ideas, which will be partially formulated and then checked for reasoning flaws by a reasoning program.（分数：17.50）(1).What does the author suggest about humans in the first paragraph?（分数：3.50）A.Humans make mistakes due to faulty reasoning.B
