大学英语四级-86及答案解析.doc
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1、大学英语四级-86 及答案解析(总分:100.00,做题时间:90 分钟)一、Reading Comprehensio(总题数:4,分数:100.00)The Internet is an international collection of computer networks that all understand a standard system of addresses and commands, connected together through backbone (中枢) systems. It was started in 1969, when the U.S. Depart
2、ment of Defense 1 a nationwide network to connect a handful of universities and contractors (订约人). The 2 idea was to increase computing capacity that could be shared by users in many locations and to find out what it would take for computer networks to 3 a nuclear war or other disasters by providing
3、 multiple paths between users. People on the ARPNET (as this nationwide network was originally called) quickly discovered that they could exchange messages and conduct electronic “conferences“ with distant colleagues for 4 that had nothing to do with the military industrial complex. If somebody else
4、 had something interesting 5 on their computer, it was a simple matter to obtain a copy (assuming the owner did not protect it). Over the years, additional networks joined which added 6 to more and more computers. The first international connections, to Norway and England, were added in 1973. Today
5、thousands of networks and millions of computers are connected to the Internet. It is growing so quickly that nobody can say 7 how many users “on the Net“. The Internet is the largest repository (知识库) of information which can provide very large network resources. The network resources can be 8 into n
6、etwork facilities resources and network information resources. The network facilities resources provide us the ability of 9 computation and communication. The network information resources provides us all kinds of information 10 , such as science, education, business, history, law, art, and entertai
7、nment, etc. A. access B. original C. divided D. survive E. debates F. established G. purposes H. genuine I. exactly J. remote K. possibility L. stored M. totally N. services O. maintain(分数:25.00)Once they decided to have children, MiShel and Carl Meissner tackled the next big issue: Should they try
8、to have a girl? It was no small matter. MiShel“s brother had become blind from a hereditary condition in his early 20s, and the Meissners had learned that the condition is a 11 passed from mothers to sons. If they had a boy, he would have a 50 per cent chance of having the condition. A girl would be
9、 12 . The British couple“s inquiries about gender selection led them in 1999 to Virginia, US where a new sperm (精子)-separation technique, called MicroSoft, was under 13 . When MiShel became pregnant, she gave birth to a daughter. They will try to have a second daughter using the technique later this
10、 year. The technique separates sperm into two groupsthose that carry the X-chromosome (producing a female baby) and those that carry the Y-chromosome (producing a male baby). The technology was developed in 1990s, but last month“s opening of a laboratory in California 14 the company“s first expansio
11、n. “We believe the number of people who want this technology is greater than those who have 15 to it,“ said Keith L. Blauer, the company“s clinical director. This is not only a 16 effective way to select a child“s gender. It also brings a host of ethical (伦理的) and practical considerationsespecially
12、for the majority of families who use the technique for 17 reasons. The clinic offers sex selection for two purposes to help couples avoid passing on a gender4inked 18 disease and to allow those who already have a child to “balance“ their family by having a baby of the opposite sex. The technology is
13、 still 19 . However, Blauer says the company has an impressive success rate: 91 per cent of the women who become pregnant after sorting for a girl are successful, while 76 per cent who sort for a boy and get pregnant are successful. The technique separates sperm based on the fact that the X-chromoso
14、me is larger than the Y-chromosome. A machine is used to 20 the size differences and sort the sperm accordingly. The result is then checked using another type of DNA analysis to ensure that it contains mostly X-or Y-bearing sperm. The desired sample is then used for artificial insemination (授精) or t
15、est tube fertilization. A. genetic B. overlapped C. marked D. unaffected E. perpetually F. investigation G. access H. feat I. disorder J. gropes K. experimental L. seemingly M. elicit N. nonmedical O. distinguish(分数:25.00)The greenhouse effect causes trouble by raising the temperature of the planet.
16、 The 21 rise is not very much, but the Earth“s ecosystem is very weak, and small changes can have large effects. It has been believed that this 22 of one degree will happen by the year 2025. This could probably 23 the North American corn belt, which produces much of the world“s grain, 24 to much hig
17、her food prices, and even less food for the Third World than they already have. However, it would also mean that some countries which are further north would be able to 25 crops they had never been able to before, although there is less land as you move north from the corn belt. The other serious wo
18、rry is that rising sea levels from the melting of the polar ice could 26 flood many countries. A rise in sea levels of one meter, which many experts are 27 by the year 2100 (and some as soon as 2030), would flood 15 percent of Egypt, and 12 percent of Bangladesh. The Maldives in the Indian Ocean wou
19、ld almost 28 disappear. Most of the countries which would suffer most from a rise in sea levels are the poor 29 states, so the islands in the Caribbean, South Pacific, Mediterranean and Indian Ocean have formed the Alliance of Small Island States, AOSIS, so they have a 30 voice in international poli
20、tics and can make the richer developed world listen to their problems. A. severely B. damage C. island D. critical E. grow F. mainland G. louder H. predicting I. rise J. completely K. geometry L. actual M. extending N. leading O. develop(分数:25.00)Many people wonder why some men want to live on the m
21、oon. It is 31 not the kind of place where most men would choose to live. But man has always moved to new areas. Some scientists hope that continued work will be done on the moon. Many experiments will be done there more 32 . Some large 33 are very easy to do in a place without air. Matter can be hea
22、ted to very high temperatures without 34 change when it is in such a place Air, dust; and clouds cannot 35 man“s view of space from the moon. The very high or very low temperatures and low gravity on the moon will be used for many experiments. One very important use of the moon will be to 36 spacesh
23、ip. Man might be able to learn much about his own body by living on the moon. He would be living in a habitat that he made for himself. Man would be in control of the 37 of life in which he lives. 38 could be removed from the air in this community. Gravity is the one thing that would not be under ma
24、n“s control. Some scientists believe the low gravity of the moon would be 39 for man. The heart would not have to work so hard. The body would need less energy to move than it does on the earth. However, the human body might change during long stays on the moon Much exercise would probably be needed
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- 大学 英语四 86 答案 解析 DOC
