第四部分：阅读理解(每题3分，共45分)

　　短文后有5道题，每题后面有4个选项。请仔细阅读短文并根据短文回答其后面的问题，从4个选项中选择1个最佳答案涂在答题卡相应的位置上。

　　Newspapers often tell us of floods in some parts of the United States.

　　Nearly every year on the great central drainages heavy rains and melting snow cause the waters to pour out the mountains and plains, to turn brooks into torrents, and to swell quiet streams into wild uncontrolled rivers. From Cairo to New Orleans, and from Pittsburgh to Paducah, the cry "River rising!" is a familiar yet fearful voice. . . When the rivers sometimes become too high or too swift to be controlled communities are flooded, families flee from their homes, croplands are washed out, and transportation comes to a halt. Hunger, disease, and death follow the wild waters.

　　Although given less publicity, the agricultural damage done by the many smaller, more frequent floods usually far exceeds the losses caused by the very grand ones. In the Central States, ditches and drains cause the flows from spring rains and melting snow to run far more rapidly than in the days before white men settled on the land. Once, excess spring flood waters emptied into lakes and swampy lands, there to be detained for slow release into stream and rivers. Now, systematic drainage has actually eliminated these natural reservoirs.

　　In the more rolling sections of the East, spring runoff was formerly absorbed and held temporarily in the porous soils beneath the unbroken expanse of forest. When large areas were converted to farm use, removal of the forest and the practice of up-and-down hill plowing deprived the soils of much of their ability to catch and store water.

　　The effects of eliminating the natural forest cover are shown in the gullied farm lands and widened stream channels found in some densely settled areas. Partly because the stream channels are more or less filled with material washed down from the uplands, and partly because storm runoff has increased, the channels are today no longer able to carry all the flow from heavy rains. This explains why the streams overtop banks far more often than in the days before settlement.

　　31. The best title for the selection would be______.

　　A. River Rising! River Rising!

　　B. Forests and Floods

　　C. Flooding in the U. S.

　　D. The Results of Flooding

　　32. All of the following cause floods EXCEPT______.

　　A. heavy rain

　　B. melting snow

　　C. increasing storm runoff

　　D. porous soil

　　33. The author states that______.

　　A. lakes and swamps once acted like natural reservoirs

　　B. up-and-down hill plowing catches and stores water

　　C. stream channels are the best carriers of water

　　D. floods are easily prevented and controlled

　　34. According to the selection, streams overtop their banks partly because______.

　　A. material from higher land is washed into them

　　B. ditches and drains lead into them

　　C. rivers become too swift

　　D. snow melts more rapidly nowadays

　　35. The floods which are given most publicity______.

　　A. cause no damage

　　B. cause the most damage

　　C. cause less agricultural damage than the many smaller, more frequent floods

　　D. far exceed the smaller, more frequent floods in agricultural loss

　　Mobile Phone and Diseases

　　A study by scientists in Finland has found that mobile phone radiation can cause changes in human cells that might affect the brain, the leader of the research team said.

　　But Darius Leszczynski, who headed the 2-year study and will present findings next week at a conference in Quebec(魁北克), said more research was needed to determine the seriousness of the changes and their impact on the brain or the body.

　　The study at Finland's Radiation and Nuclear Safety Authority found that exposure to radiation from mobile phones can cause increased activity in hundreds of proteins in human cells grown in a laboratory, he said.

　　“We know that there is some biological response. We can detect it with our very sensitive approaches, but we do not know whether it can have any physiological effects on the human brain or human body,” Leszczynski said.

　　Nonetheless the study, the initial findings of which were published last month in the scientific journal Differentiation, raises new questions about whether mobile phone radiation can weaken the brain's protective shield against harmful substances.

　　The study focused on changes in cells that line blood vessels and on whether such changes could weaken the functioning of the blood-brain barrier, which prevents potentially harmful substances from entering the brain from the bloodstream, Leszczynski said.

　　The study found that a protein called hsp27 linked to the functioning of the blood-brain barrier showed increased activity due to irradiation and pointed to a possibility that such activity could make the shield more permeable(能透过的), he said.

　　“Increased protein activity might cause cells to shrink—not the blood vessels but the cells themselves—and then tiny gaps could appear between those cells through which some molecules could pass. ” he said.

　　Leszczynski declined to speculate on what kind of health risks that could pose, but said a French study indicated that headache, fatigue and sleep disorders could result.

　　“These are not life-threatening problems but can cause a lot of discomfort,” he said, adding that a Swedish group had also suggested a possible link with Alzheimer's disease.

　　“Where the truth is do not know,” he said.

　　Leszczynski said that he, his wife and children use mobile phones, and he said that he did not think his study suggested any need for new restrictions on mobile phone use.

　　36　According to Leszczynski, how does mobile phone affect one's health? _________

　　A　Mobile phone radiation can increase protein activities and such activities can make the protective shield more permeable.

　　B　Mobile phone radiation can shrink the blood vessels and prevent blood from flowing smoothly.

　　C　Mobile phone radiation will bring stress to people exposed to it.

　　D　Mobile phone radiation kills blood cells at a rapid speed.

　　37　What's the result of the French study? _________

　　A　The harm of mobile phone radiation is life-threatening.

　　B　Mobile phone may affect one's normal way of thinking.

　　C　Sleep disorders could result from mobile phone radiation.

　　D　A protein called hsp27 is killed by mobile phone radiation.

　　38　What kind of disease is not caused by the use of mobile phone? _________

　　A　Fatigue.

　　B　Headache.

　　C　Alzheimer's disease.

　　D　Tuberculosis.

　　39　According to the passage, what would be the future of the use of mobile phone? _________

　　A　People will be forbidden to use mobile phone.

　　B　People dare not use mobile phone because of its radiation.

　　C　People will continue to use mobile phone.

　　D　There will be new restrictions on the use of mobile phone.

　　40　Which of the following is NOT true according to the passage? _________

　　A　The research in Finland found that mobile phone radiation will affect one's brain.

　　B　Mobile phone radiation can cause increased activity in hundreds of protein in human cells.

　　C　Increased protein activity might cause cells to shrink.

　　D　Lszczynski forbid his wife and children to use mobile phone after his research.

　　Electronic Mail (E-mail)

　　During the past few years, scientists the world over have suddenly found themselves productively engaged in task they once spent their lives avoiding-writing, any kind of writing, but particularly letter writing. Encouraged by electronic mail's surprisingly high speed, convenience and economy, people who never before touched the stuff are regularly, skillfully, even cheerfully tapping out a great deal of correspondence.

　　Electronic networks, woven into the fabric of scientific communication these days, are the route to colleagues in distant countries, shared data, bulletin boards and electronic journals. Anyone with a personal computer, a modem and the software to link computers over telephone lines can sign on. An estimated five million scientists have done so with more joining every day, most of them communicating through a bundle of interconnected domestic and foreign routes known collectively as the Internet, or net.

　　E-mail is starting to edge out the fax, the telephone, overnight mail, and of course, land mail. It shrinks time and distance between scientific collaborators, in part because it is conveniently asynchronous (writers can type while their colleagues across time zones sleep; their message will be waiting). If it is not yet speeding discoveries, it is certainly accelerating communication.

　　Jeremy Bernstei, the physicist and science writer, once called E-mail the physicist's umbilical cord. Lately other people, too, have been discovering its connective virtues. Physicists are using it; college students are using it, everybody is using it, and as a sign that it has come of age, the New Yorker has celebrated its liberating presence with a cartoon-an appreciative dog seated at a keyboard, saying happily, “On the Internet, nobody knows you're a dog.”

　　41　The reasons given below about the popularity of E-mail can be found in the passage EXCEPT __________.

　　A　direct and reliable

　　B　time-saving in delivery

　　C　money-saving

　　D　available at any time

　　42　How is the Internet or net explained in the passage? __________

　　A　Electronic routes used to read home and international journals.

　　B　Electronic routes used to fax or correspond overnight.

　　C　Electronic routes waiting for correspondence while one is sleeping.

　　D　Electronic routes connected among millions of users, home and abroad.

　　43　What does the sentence “If it is not yet speeding discoveries, it is certainly accelerating communication” most probably mean? __________

　　A　The quick speed of correspondence may have ill-effects on discoveries.

　　B　Although it does not speed up correspondence, it helps make discoveries.

　　C　It quickens mutual communication even if it does not accelerate discoveries.

　　D　It shrinks time for communication and accelerates discoveries.

　　44　What does the sentence “On the Internet, nobody knows you're a dog.”imply in the last paragraph? __________

　　A　Even dogs are interested in the computer.

　　B　E-mail has become very popular.

　　C　Dogs are liberated from their usual duties.

　　D　E-mail deprives dogs of their owners' love.

　　45　What will happen to fax, land mail, overnight mail, etc. according to the writer? __________

　　A　Their functions cannot be replaced by E-mail.

　　B　They will co-exist with E-mail for a long time.

　　C　Less and less people will use them.

　　D　They will play a supplementary function to E-mail.