1、考博英语-114 及答案解析(总分：100.00，做题时间：90 分钟)一、BPart Reading (总题数：4，分数：20.00)Valvular heart diseases are quite common, essentially resulting in impaired blood flow and were very difficult to treat. Some 30 years ago, it became possible to replace .diseased valves with prostheses to impose a greater control o
2、ver blood flow.Early devices were of the mechanical variety, in which devices like ball-in-a-cage or tilting disc would be used to allow blood to flow under near-normal conditions. Although a few mechanical problems were encountered in the early days, the major difficulty lay with the tendency for a
3、ny foreign material to initiate a blood clot. So, all valve recipients have to be given anticoagulant therapy. This is not particularly desirable for the patients, who may develop bleeding problems, and in any case is not always successful.Although good results are achieved with these valves, it was
4、 considered necessary to develop alternatives and the direction was that of natural tissues. Its not possible to transplant heart valves untreated because of rejection phenomena, but it became apparent that collagenous tissue could be cross-linked by glutaraldehyde and prepared in the form of a hear
5、t valve. Two sources of tissue were considered for this purpose, bovine pericardium ( collagenous tissue derived from the wall of a cows heart) and porcine valves (heart valves taken from pigs) and the resulting “bioprosthetic valve“ appeared to be very promising. It was particularly important that
6、these patients didnt need anticoagulation. Unfortunately, these valves have not proved very durable, the cross-linked collagen suffering from slow calcification and deterioration so most of the replacement valves themselves need to be replaced within a decade.This would tend to suggest that the mech
7、anical valves give superior performance, notwithstanding the anticoagulation problem, and a move back towards their use might have been expected. However, most of the valves in current use incorporate an alloy( usually Stellite) forthe housing, and a carbon coated occuluder. The complex shapes of so
8、me of the housing have required combinations of casting and welding technologies to be used in their construction and serious problems have arisen with a valve design from one manufacturer, where a small number of catastrophic fractures have occurred within the housing. In patients where this valve
9、has been used to treat aortic valve disease, this fracture is usually fatal and although the risks are small, the problem is important to the industry.Also, at a time when this dichotomy is exercising the minds of surgeons, scientists and regulatory bodies alike, the emergence of the disease BSE in
10、cattle has placed even further restrictions on the use of animal tissue for this type of application and the whole question of prosthetic heart valves has been turned from a reasonable successful example of reconstructive implant surgery to a very confused area. This serves to highlight some of the
11、very varied problems of facing the use of biomaterials.（分数：5.00）(1).This passage is extracted from an article written by an expert on _.（分数：1.00）A.surgical equipmentB.heart diseasesC.materials for surgical implantsD.mechanical valve manufacturing(2).What does “this dichotomy“ in last paragraph refer
12、 to?（分数：1.00）A.Cows heart wall or pigs heart valve.B.Tissues or device.C.Housing or occuluder.D.Anticoagulation or calcification.(3).Which of the following can be classified as a mechanical valve?（分数：1.00）A.Tilting disc device.B.Aortic valve.C.Collagenous tissue.D.Porcine valve.(4).Which of the foll
13、owing does nut need to he considered in the area of heart valve replacement?（分数：1.00）A.Rejection phenomena.B.Anticoagulation.C.Durability.D.Regulatory bodies.Water will evaporate from any wetted surface. A .significantly large fraction of the rainfall that falls on land is returned to the atmosphere
14、 in this fashion. In addition water is assimilated by root systems of growing plants and is later transpired from the leaf surfaces by a process essentially identical to evaporation. The two effects, evaporation and transpiration, cannot be individually discriminated for their effectiveness in retur
15、ning rainfall to the atmosphere, but their sum contribution can be evaluated and is usually called the evapotranspiration factor. The fraction of rain falling on the United States that is returned to the atmosphere by evapotranspiration, for example, is 70 percent; for the world as a whole, approxim
16、ately 62 percent. In arid countries such as Australia the fraction is larger, and in less arid areas such as the United Kingdom it is lower. Water returned to the atmosphere by evapotranspiration is unavailable to man, except in, the sense that useful plants may be grown in the place of useless ones
17、. It cannot be trapped and redistributed for industrial or other purposes.In regions of low rainfall, plant cover will develop to a point where all precipitation is used in evapotranspiration and none remains for stream now. Seasonal rainfalls provide a qualifier for this statement because streams w
18、ill flow even in the most arid areas during periods of maximum rainfall. In general, if the potential evapotranspirationthat which would result from the maximum plant cover a region could support under ideal circumstancesshould exceed the precipitation, overland stream flow ceases. Conversely, if ev
19、apotranspiration is less than precipitation, runoff is generated.The amount by which precipitation exceeds evapotranspiration is the perennial yield of stream flow water, and this is the usable fraction of rain and snowfall. Across the entire United States the water yield amounts to 30 percent of th
20、e total rainfall, or approximately 1.771015 liters per year. But when we consider the distribution of water deficiencies and surpluses we find that essentially the entire eastern half of the United States, together with a small region in the Pacific northwest, enjoys water surplus, while most of the
21、 country to west of the Mississippi is water- deficient and arid.（分数：5.00）(1).According to the passage, a greater fraction of rainfall on the globe we live comes from_.（分数：1.00）A.the evaporated and transpired water from the earth itselfB.the wet atmosphere above in the skyC.returning rainfall to the
22、 atmosphereD.the mixture of wet and dry air(2).If the amount of evaporated water is less than the amount of water falling on, then _.（分数：1.00）A.stream flow will appearB.the surplus of water will run offC.flood will be generatedD.the plant has to transpire the surplus(3).Which of the following is tru
23、e?（分数：1.00）A.Water evaporated to atmosphere is unavailable to man because it is from useless plants.B.Man can interfere with water evaporation by growing some plants.C.Man can recycle evaporated water to grow useful plants.D.Useful plants can collect the evaporated water which will be used for other
24、 purpose.(4).According to the passage, the water that is available to us is _.（分数：1.00）A.equal to the precipitationB.purified by useful plantsC.the fraction of water that is not evaporatedD.the rain falling and the snow meltedAids in South Africa is threatening to become a problem. At the end of 199
25、3, 4.25% of South African adults were HIV positive. By the end of 1994, the figure was 7.57%.This increase in a year is the largest for the spread of the virus in Africa and possibly the world, and it seems certain that 12% or more of the population will be HIV positive by Christmas.In the worst hit
26、 area, the HIV positive rate now tops 20%. It seems South Africa is moving rapidly towards the catastrophic 35% levels of infection in East Africa. This will be the first time that the virus will have become so widespread in a sophisticated, industrialized country.Both the present and preceding gove
27、rnments should bear responsibility; each was aware of the crisis and did almost nothing. There is no public campaign to promote safe sex, for example. The apartheid regime was too conscious of religious sensitivities to organize an explicit anti-Aids campaign, and the African National Congress is fa
28、r too nervous about traditional African attitudes to sex.A survey of black women in Johannesburg revealed that 75% were willing to accept condoms if they could persuade their partners to use them, but that in practice only 2% had managed to doso. Women are the chief victims with the highest HIV-posi
29、tive rates among nurses and teachers.Many African men have responded to the epidemic by choosing younger and younger partners. There is even a myth that sex with a young enough girl can cure an Aids-stricken male. Inevitably young women are the hardest hit, a phenomenon compounded by the high incide
30、nce of rape. More than 100 rapes are reported to the authorities every day, although this figure is believed to represent a minority of actual cases.Despite the spread of the virus, the statistics manage to struggle on to only about page six of most South African newspapers because the crisis is sti
31、ll in “phoney war“ stage although there are more than 1.8 million HIV-positive South Africans, relatively few of them have developed Aids. Doctors say the virus seems to be taking longer to move through its cycle here, perhaps because South Africans with their higher standards of living, are healthi
32、er and therefore more resistant than people further north in Africa.Without doubt, the present air of complacency will vanish as soon as high profile members of the elite begin to be affected and the implications for the economy sink in. Moreover, the spread of the virus may greatly damage the prese
33、nt racial reconciliation in South Africa, since Aids is now overwhelmingly a disease of blacks, and many whites are beginning to see almost every African as an Aids risk.（分数：5.00）(1).According to the passage, which of the following is not blamed as the factor that prevents anti- Aids campaign?（分数：1.
34、00）A.Over sensitive to religious belief.B.Traditional African attitude to sex.C.High standard of living.D.The myth about having intercourse with a virgin.(2).It is suggested in the passage that _.（分数：1.00）A.Aids case is rare in highly advanced countriesB.South Africa has the highest Aids rate in the
35、 worldC.the press tried to report a phoney warD.minority young women are more often raped(3).Which group of the following people tends to have highest rate of Aids?（分数：1.00）A.The black elite.B.Women not using condoms.C.Aids-stricken black male.D.Young black women.(4).What does “the statistics manage
36、 to struggle on to only about page six of most South African newspapers“ imply?（分数：1.00）A.Page six of most South African newspapers usually carries important stories.B.The issue concerned has not been boosted to the top of public attention.C.Its hard to establish statistics on page six of South Afri
37、can newspapers.D.Not many of positive persons developed Aids.(5).According to the passage, with the increasing rate of Aids, _.（分数：1.00）A.people on the top of the social ladder cant escape the infectionB.people will continue to be complacentC.people will realize the consequences brought to economyD.
38、whites will alienate the black moreWhen I became president of the University of Michigan, affirmative action in higher education was under siege. Buoyed by a successful lawsuit against the University of Texas law schools admission policy and by ballot initiatives such as Californias Proposition 209,
39、 which outlawed race as a factor in college admissions, the opponents set their sights on affirmative-action programs at college across the country.The rumor that Michigan would be the next target in this campaign turned out to be correct. I believed strongly that we had no choice but to mount the b
40、est legal defense ever for diversity in higher education and take special efforts to explain this complex issue, in simple and direct language, to the American public. There are many mispereeptions about how race and ethnieity are considered in college admissions. Competitive colleges and universiti
41、es are always looking for a mix of students with different experiences and backgrounds academic, geographic, international, socioeconomic, athletic, public-service oriented, and, yes, racial and ethnic.It is true that in sorting the initial rush of applications, large universities will give “points“
42、 for various factors in the selection process in order to ensure fairness as various officers review applicants. Opponents of Michigans undergraduate system complain that an applicant is assigned more points for being black, Hispanic, or Native American than for having a perfect SAT score. This is t
43、rue, but it trivializes the real issue: whether, in principle, race and ethnicity are appropriate considerations. The simple fact about the Michigan undergraduate policy is that it gives overwhelming weight to traditional academic factors some 110 out of a total of 150 points. After that, there are
44、some 40 points left for other factors, of which 20 can be allocated for race or socioeconomic status.Race has been a defining element of the American experience. The historic Brown v. Board of Education decision is almost 50 years old, yet metropolitan Detroit is more segregated now than it was in 1
45、960. The majority of students who each year arrive on a campus like Michigan graduated from virtually all-white or all-black high schools. The campus is their first experience living in an integrated environment.Diversity is not merely a desirable addition to a well-rounded education. It is as essen
46、tial as the study of the Middle Ages, of international politics, and of Shakespeare. For our students to better understand the diverse country and world they inhabit, they must be immersed in a campus culture that allows them to study with, argue with, and become friends with students who may be dif
47、ferent from them. It broadens the mind, and the intellect-essential goals of education.Reasonable people can disagree about affirmative action. But it is important that we do not lose the sense of history, the compassion and the largeness of vision that defined the best of the civil-rights era, whic
48、h has given rise to so much of what is good about America today.（分数：5.00）(1).This passage is mainly_.（分数：1.00）A.explanativeB.descriptiveC.argumentativeD.narrative(2).Whats the thesis of the passage?（分数：1.00）A.Affirmative action was under siege.B.Diversity is essential.C.More points should be given t
49、o the black.D.Admission policy should be reformed.(3).Which of the following is not the authors argument?（分数：1.00）A.Competitive colleges and universities need a mix of students with different experiences and background.B.More points should be allocated for race or socioeconomic status.C.In admitting students, traditional academic factors are weighed more.D.Diversity has given America what is so good about it.(4).In the passage, the author criticized many misconceptions. Which of the following is not the one he criticized?（分数：1.00）A.
