第3部分：概括大意与完成句子（第23～30题，每题1分，共8分)
下面的短文后有2项测试任务：（1)第23～26题要求从所给的6个选项中为第1～4段每段1选择个最佳标题；（2)第27～30题要求从所给的6个选项中为每个句子确定1个最佳选项。
Chimpanzees
1Chimpanzees （黑猩猩) will soon be extinct （灭绝)。 If the present rate of hunting and habitat （栖息地) destruction continues， then within 20 years， there will be no chimpanzees living in the wild. But this is more than an environmental or moral tragedy （悲剧)。 Chimpanzee extinction may also have profound implications （含意) for the survival of their distant relatives - human beings.
2In 1975 the biologist Marie-Claire King and Allan Wilson discovered that the human and chimpanzee genomes （基因组) match by over 98%. Compare this to the mouse， used as model for human disease in lab tests， which shares only 60% of its DNA with us. In fact， chimpanzees are far more similar to humans than they are to any other species of monkey. As well as resembling us genetically， chimps are highly intelligent and able to use tools. These facts alone should be enough to make 医.学.全.在.线www.med126.comprotection of chimps an urgent priority （优先)。 But there is another， more selfish reason to preserve the chimp.
3The chimpanzees' trump card （王牌) comes in the field of medical research. Chimpanzees are so similar to humans that veterinarians （兽医) often refer to human medical textbooks when treating them. Yet chimpanzees do show differences in several key areas. In particular， chimps are much more resistant to a number of major diseases. It is this ability that is so interesting.
4For example， chimps seem to show a much higher resistance than humans to HIV， the virus that causes AIDS. Indeed， their use as experimental animals in AIDS research has declined because they are so resistant.
5By sequencing the chimp genome and pinpointing （找到) the place where the chimpanzee DNA sequence differs from that of humans， scientists hope to be able to discover which part of the genetic code gives chimps their increased resistance to some diseases. This， they hope， will allow them to develop new and more effective treatments for the human forms of these diseases. Such treatments could include the production of new drugs or even the alteration （改变) of the human genetic sequence. The recently completed human genome sequencing project has shown that such an effort is now well within our reach.
23 Paragraph 1
24 Paragraph 2
25 Paragraph 3
26 Paragraph 4
A Reasons for HIV resistance
B Implications of chimpanzee extinction for humans
C Effective AIDS treatment
D Genetic similarities between chimps and humans
E Chimps' resistance to HIV
F Genetic differences between chimps and humans
27 Chimpanzee extinction may affect
28 There is a difference of less than 2% between the chimp and
29 Scientists suspect that genes.PlaY a significant role in protecting chimps from getting
30 The discovery of the genetic code of chimps will be helpful to
A some human disease treatments
B some diseases
C human survival
D human genomes
E key areas
F healthier lifestyle
第4部分：阅读理解（第31～45题，每题3分，共45分)
下面有3篇短文，每篇短文后有5道题。请根据短文内容，为每题确定1个最佳选项。
第一篇
Water
The second most important constituent （构成成份) of the biosphere （生物圈) is liquid water. This can only exist in a very narrow range of temperatures， since water freezes at 0℃ and boils at 100℃。 Life as we know it would only be possible on the surface of a planet which had temperatures somewhere within this narrow range.
The earth's supply of www.med126.comwater probably remains fairly constant in quantity. The total quantity of water is not known very accurately， but it is about enough to cover the surface of the globe to a depth of about two and three-quarter kilometers. Most of it is in the form of the salt water of the oceans - about 97 per cent. The rest
is fresh， but three-quarters of this is in the form of ice at the Poles and on mountains， and cannot be used by living systems until melted. Of the remaining fractional which is somewhat less than one per cent of the whole， there is 10-20 times as much stored underground water as there is actually on the surface. There is also a tiny， but extremely important fraction of the water supply which is present as water vapor in the atmosphere.
Water vapor in the atmosphere is the channel through which the whole water
circulation （循环) of the biosphere has to pass. Water evaporated （蒸发) from the surface of the oceans， from lakes and rivers and from moist （潮湿的) earth is added to it. From it the water comes out again as rain or snow， falling on either the sea or the land. There is， as might be expected， a more intensive evaporation per unit area over the sea and oceans than over the land， but there is more rainfall over the land than over the oceans， and the balance is restored by the runoff from the land in the form of rivers.www.med126.com
31 Liquid water only exists
A in the center of the earth.
B on the surface of our planet.
C in a very narrow range of temperatures.
D in the coastal areas of the earth.
32 The total quantity of water on Earth
A remains almost unchanged.
B has greatly increased in recent years.
C is decreasing constantly.
D is affected by global warming.
33 Most of the fresh water on Earth
A is stored underground.
B is in the form of ice at the Poles and on mountains.
C is found in rivers and lakes.
D comes from the rain.
34 The word “fraction” in the second paragraph means
A a very small amount.
B a large area.
C an important system.
D a major source of information
35 There is more of rainfall
A over the mountains than over the rivers.
B over the rivers than over the mountains
C over the oceans than over the land.
D over the land than over the oceans.
