题目内容
（请给出正确答案）
Scientists say it may be ten years______this medicine was put to use.
A．since
B．before
C．after
D．when
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更多“Scientists say it may be ten y…”相关的问题
The article does not say whether the scientists' experiments with dogs have ______.
A．benefited animals other than dogs
B．served man
C．helped other dogs
D．contributed to medical knowledge
A.would be ideal
B.would have been ideal
C.will be ideal
D.will have been ideal
阅读下列短文，然后根据短文的内容从 55～57 小题的四个选择项中选出最佳的一项。
B
Scientists have searched for many years for a method to tell whether a volcano（火山）explosion will be small or large. Now，four scientists say they have discovered something in lava（熔岩）that will help do this. They did the research on Mount Unzen on the southern Japanese island of Kyushu.
Mount Unzen exploded in November，1990. Since then，more explosions have killed 43 people and destroyed the homes of more than 2，000 others. The volcano is still active today.
The scientists say the lava of the volcano contains high level of an element（成份），which is a sign of the presence of the lava from deep in the earth，not from the surface. They say it shows that the lava coming directly from inside the earth is connected with huge explosions instead of smaller ones.
The scientists examined the lava from 18 explosions of Mount Unzen that took place during many thousands of years. They also studied the lava from other volcanoes in the area that are older than Mount Unzen. The lava studied came from both large and small explosions. The scientists found that large explosions contained more of the element than small ones. The scientists say if they had known this two years earlier，they could have warned the people living in the area near Mount Unzen and saved many lives.
第 55 题 From the passage we learn that Mount Unzen is the name of ______.
A．a huge volcano explosion
B．a Japanese island
C．an active volcano
D．a kind of lava
Asteroids are different forms of the meteoroids that race across the night sky. Most orbits the sun far from Earth and don't threaten us. But there are also thousands of asteroids whose orbits put them on a violent coming course together with Earth.
Buy $ 50 million worth of new telescopes right now. Then spend $10 mil]ion a year for the next 25 years to locate most of the space rocks. By the time we spot a fatal one, the scientists say, we'll have a way to change its course.
Some scientists favor pushing asteroids off course with nuclear weapons. But the cost wouldn't be cheap.
Is it worth it？ Two things experts consider when judging any risk are: 1) How likely the event is; and 2) How bad the consequences if the event occurs. Experts think asteroids big enough to destroy lots of life might strike Earth once every 500,000 years. Sounds pretty rare but if one did fall it would be the end of the world. "If we don't take care of these big asteroids, they'll take care of us. "Says one scientist. "Its that simple."
The cure, though, might be worse than the disease, Do we really want fleets of nuclear weapons silting around on Earth？ "The world has less to fear from doomsday rocks than from a great nuclear fleet set against them. "Said a New York Times article.
What does the passage say about asteroids and meteoroids？
A．They are heavenly bodies similar in nature.
B．There are more asteroids than meteoroids.
C．They are heavenly bodies different in composition.
D．Asteroids are more mysterious than meteoroids.
Research experience is an essential element of hiring and promotion at the research university because it is the emphasis on research that distinguishes such a university from an arts college. Some professors, however, neglect teaching for research, and that presents a problem.
Most research universities reward outstanding teaching, but the greatest recognition is usually given for achievements in research. Part of the reason is the difficulty of judging teaching. A highly responsible and tough professor is usually appreciated by top students who want to be challenged, but disliked by those whose records are less impressive. The mild professor gets overall ratings that are usually high, but there is a sense of disappointment on the part of the best students, exactly those for whom the system should present the greatest challenges. Thus, a university trying to promote professors primarily on the basis of teaching qualities would have to confront this confusion.
As modem science moves faster, two forces are exerted on professors: one is the time needed to keep up with the profession; the other is the time needed to teach. The training of new scientists re quires outstanding teaching at the research university as well as the arts college. Although scientists are usually "made" in the elementary schools, scientists can be "lost" by poor teaching at the college and graduate school levels. The solution is not to separate teaching and research, but to recognize that the combination is difficult but vital. The title of professor should be given only to those who profess, and it is perhaps time for universities to reserve it for those willing to be an earnest part of the community of scholars. Professors unwilling to teach can be called "distinguished research investigators, "or something else.
The pace of modem science makes it increasingly difficult to be a great researcher and great teacher. Yet many are described in just those terms. Those who say we can separate teaching and re search simply do not understand the system, but those who say the problem will disappear are not fulfilling their responsibilities.
What idea does the author want to convey in the first paragraph？
A．It is wrong to overestimate the importance of teaching.
B．Teaching and research are contradictory to each other.
C．Research can never be emphasized too much.
D．The relationship between teaching and research should not be simplified.
Reports from China say the Chinese want closer ties between China and the U.S. and Western Europe. A group of Chinese scientists will start its ten-nation tour next month.
Here in Miami, the mayor is still meeting with the leaders of the teachers' union to try to find a way to end the strike. City schools are still closed after two weeks.
In news about health, scientists in California report findings of a relationship between the drinking of coffee and the increase of heart disease among women. According to the report in the American Medical Journal (= magazine) , the five-year study shows this: Women who drink more than two cups of coffee a day have a greater chance of having heart disease than women who do not.
In sports the Chargers lost again last night. The BBS beat them 1 to nothing. The Wingers had better results. They beat the Rifles 7 to 3. It was their first win in their last five matches.
That's the News on the Hour. And now back to more easy listening with Jan Singer.
Who gave the News on the Hour？
A．The President and First Lady.
B．Ed Wilson.
C．Scientists in California.
D．Jan Singer.
根据下面内容，回答题：
Scientists in the UK have announced that the piranhafish"s reputation 21 a fearsome 22 may well not be deserved. The fish， which is found in the Amazon in Brazil， have been 23 as deadly carnivores（食肉动物 ） that work in shoals to overwhelm their prey and strip it of its flesh in seconds.
However， experts 24 St Andrews University say that piranhas are omnivores（杂食动物） that mainly eat fish， plants and insects. They form. big groups not to hunt but to defend 25 against other predators， according to the team.
"Previously it was thought piranhas shoaled as it 26 them to form. a cooperative hunting group，" said Professor Anne Magurran. " 27， we have found that it is primarily a defensive behavior. "
Piranhas can be attacked by animals 28 dolphins， caimans and large fish， so forming a shoal is a good way of 29 being killed. Piranhas of 30 age stay in the middle of the group for 31 and the 32 of the shoal differs according to the level of 33 When the water level is 34， the fish form. small groups as there is space to escape， but when the water level drops， they form. large groups as protection 35 predators.
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A.as
B.as if
C.as though
D.since
A．detected
B．caught
C．disclosed
D．revealed
A study published recently in the journal Nature shows that air-borne leaded gas emissions from the United States were the leading contributor to the high concentration of lead in the snow in Greenland. The new study is a result of the continued research led by Dr. Charles Boutron, an expert on the impact of heavy metals on the environment at the National Center for Scientific Research in France. A study by Dr. Boutron published in 1991 showed that lead levels in arctic (北极的) snow were declining.
In his new study, Dr. Boutron found the ratios of the different forms of lead in the leaded gasoline used in the United States were different from the ratios of European, Asian and Canadian gasolines and thus enabled scientists to differentiate the lead sources. The dominant lead ratio found in Greenland snow matched that found ingasoline from the United States.
In a study published in the journal Ambio, scientists found that levels in soil in the Northeastern United States had decreased markedly since the introduction of unleaded gasoline.
Many scientists had believed that the lead would stay in soil and snow for a longer period.
The authors of the Ambio study examined samples of the upper layers of soil taken from the same sites of 30 forest floors in New England, New York and Pennsylvania in 1980 and in 1990. The forest environment processed and redistributed the lead faster than the scientists had expected.
Scientists say both studies demonstrate that certain parts of the ecosystem respond rapidly to reductions in atmospheric pollution, but that these findings should not be used as a license to pollute.
The study published in the journal Nature indicates that
A．the Clean Air Act has not produced the desired results.
B．lead deposits in arctic snow on the increase.
C．lead will stay in soil and snow longer than expected.
D．the U.S. is the major source of lead pollution in arctic snow.
【B5】 he, however, might tremble at the 【B6】 of what he is about to do. Together with another two scientists, he is publishing a paper which not only 【B7】 that one group of humanity is more intelligent than the others, but explains the process that has brought this about. The group in 【B8】 are a particular people originated from central Europe. The process is natural selection.
This group generally do well in IQ test, 【B9】 12-15 points above the 【B10】 value of 100, and have contributed 【B11】 to the intellectual and cultural life of the West, as the 【B12】 of their elites, including several world-renowned scientists, 【B13】. They also suffer more often than most people from a number of nasty genetic diseases, such as breast cancer. These facts, 【B14】, have previously been thought unrelated. The former has been 【B15】 to social effects, such as a strong tradition of 【B16】 education. The latter was seen as a (an) 【B17】 of genetic isolation. Dr. Cochran suggests that the intelligence and diseases are intimately 【B18】. His argument is that the unusual history of these people has 【B19】 them to unique evolutionary pressures that have resulted in this 【B20】 state of affairs.
【B1】
A．selected
B．prepared
C．obliged
D．pleased
