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Unless we spend money to spot and prevent asteroids(小行星) now, one might crash into Earth and destroy life as we know it , say some scientists. Asteroids are bigger versions of the meteoroids(流星) that race across the night sky. Most orbit the sun far from Earth and don’t threaten us. But there are also thousands of asteroids whose orbits put them on a collision course with Earth. Buy $50 million worth of new telescopes right now. Then spend $10 million 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; 2) How bad the consequences if the event occurs. Experts think an asteroid 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. “It’s that simple.” The cure, though, might be worse than the disease. Do we really want fleets of nuclear weapons sitting around on Earth? “The world has less to fear from doomsday(毁灭性的) rocks than from a great nuclear fleet set against them,” said a New York Times article. 1.What does the passage say about asteroids and meteoroids? A. They are heavenly bodies different in composition. B. They are heavenly bodies similar in nature. C. These are more asteroids than meteoroids. D. Asteroids are more mysterious than meteoroids. 2.What do scientists say about the collision of an asteroid with Earth? A. It is unlikely but the danger exists. B. Such a collision might occur once every 25 years. C. Collision of smaller asteroids with Earth occur more often than expected. D. It’s still too early to say whether such a collision might occur. 3.What do people think of the suggestion of using nuclear weapons to alter the course of asteroids? A. It sounds practical but it may not solve the problem. B. It may create more problems than it might solve. C. It is a waste of money because a collision of asteroids with Earth is very unlikely. D. Further research should be done before it is proved applicable. 4.We can conclude from the passage that ________. A. while pushing asteroids off course nuclear weapons would destroy the world B. asteroids racing across the night sky are likely to hit Earth in the near future C. the worry about asteroids can be left to future generations since it is unlikely to happen in our lifetime D. workable solutions still have to be found to prevent a collision of asteroids with Earth
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The journey to the moon had been the first step toward future exploration(探险) in space. The distance between the Moon and Earth is very short indeed when compared with the distances between Earth and the other planets. Mars, the nearest planet to Earth is millions of miles away. Traveling to the planets will be man’s next aim. Such travels will be more challenging than the trip to the moon and certainly more adventurous. Recently, two American spaceships, Vikings 1 and 2, landed on Mars trying to discover whether that planet has any life on it. So far the signs of life on Mars has neither confirmed(确认) nor ruled out. Russians have discovered that the surface of Venus(金星) is so hot that it is almost certain that there is no life there. Also the atmosphere of Venus is extremely dense(稠) and the pressure is nearly a hundred times greater than that of the Earth’s atmosphere. Scientists believe man may find planets which have the same conditions as those we have on Earth, but man should realize Earth will be his only home for a long time and begin to love and care for it. 1.According to the passage, traveling to the planets will be ________. A. much easier and even more interesting B. far more exciting and dangerous C. man’s final aim D. man’s first step 2.Which of the following is Not true? A. Mars is nearer to the earth than the moon. B. The moon is much nearer to the earth than Mars. C. Of all the planets, Mars is the nearest to the earth. D. All the planets are much farther to the earth. 3.From the passage, we can guess ________. A. there is life on Mars B. there is no life on Mars C. the atmosphere of Mars is not so dense as that of Venus D. scientists will have little hope to find the answers 4.Man can live on under the conditions of _______. A. much too hot surface B. the same pressure as we get on earth C. normal atmosphere as we have on earth D. both B and C
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Early in the morning of June 29, 1991, Carrier and Morgenstern were watching the field. Although they could see nothing through the thick fog, they kept their camera running. By 6 a.m. the fog began to lift. A remarkable pair of circles had been flattened. Stalks (主茎) were bent but not broken. Outside the circles the wheat was untouched. Muddy though the field was, there were no footprints or other marks. The circles seemed to have come from nowhere. “I can’t explain it at all,” Mike Carrier said to himself with his eyes wide open. Carrier is not alone since the early 1980s, more than 2000 circles have appeared in farmer’s fields. Most circles form at night between May and August. Some believe the circles are caused by deer or some other animals. Others think of UFOs. “The circles are messages given by those who come from outer space,” says Michael Green. “Perhaps they are trying to get in touch with us.” Pat Delgado has done research on crop circles since 1981. He believes that they are caused by “some form of earth energy.” Most scientists think that there’s no scientific basis to back up Green’s or Delgado’s theories. Some of them say, “ We think they’re nothing but hoax(骗局).” In September 1991, Doug Bower and Dave Chorley told newsmen that since 1979 they had made circles throughout southern England to fool people who believed in UFOs. Since the early 1980s, Dr. Terence Meaden has visited more than1000 circles. Now he thinks he may have the answer. He believes true crop circles are made by vortex(旋风) which can flatten the crop in circular patterns. Now crop circles are still found in southern England each summer. Are they really the traces of UFOs? 1.On the morning of June 29, 1991, Carrier and Morgensern hoped to ________. A. record the important thing B. draw a conclusion C. find a secret of nature D. see something funny 2.When he saw the crop circle, Mike Carrie was ________. A. satisfied B. frightened C. surprised D. interested 3.Most scientists consider that theories of Green and Delgado are ________. A. meaningful B. reasonable C. instructive D. against the laws of science 4.According to the article we may know that all the crop circles ________. A. are made by those who come from outer space B. are nothing but hoaxes C. are not hoaxes D. can be explained by scientists
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Damage to Ozone layer Gets Worse In the middle of winter, when snow is falling in many parts of the United States, scientists have sounded a warning to people who plan to spend many hours in the sun this summer. The warning is: The sun’s summertime rays are more dangerous than once thought. A team of scientists from 80 nations recently reported to the United Nations that a layer of ozone (臭氧层) in the atmosphere, which protects humans from harmful levels of ultraviolet（紫外线） radiation, will be thinner over the United States this summer. The thinner layer allows more ultraviolet rays from the sun to reach Earth. The extra amount of ultraviolet radiation could cause an increase in the number of cases of skin cancer. Scientists first became concerned about the ozone layer in the mid-1980s when a hole was discovered in the layer above Antarctica during the winter. The hole was caused by chemicals used in refrigerators and air conditioners. When these chemicals are sent out into the atmosphere, they produce gases that destroy the ozone. Concern about the protective ozone layer rose more recently when data(数据) from satellites and ground stations showed that ozone levels were dropping over areas other than Antarctica. Low ozone levels were recorded in the spring and summer over the United States and over other populated areas in the world. Although many countries have already begun stopping the use of ozone destroying chemicals, the new findings are expected to advance the timetable for a total ban(禁止) of the chemicals. 1.The scientists have observed the ozone layer ________. A. since 1980 B. since last winter C. for about 20 years D. for about one year 2.The ozone layer in the atmosphere can ________. A. do a lot of good to human beings in many ways. B. protect humans from diseases caused by bad weather. C. do a lot of harm to human beings in the summer-time. D. protect humans from harmful levels of ultraviolet radiation. 3.Scientists first found that there was a hole in the ozone layer ________. A. above Arctic during the winter in the mid-1980s B. above Antarctica during the winter in the mid-1980s C. over somewhere in the north of the equator in 1980 D. over the U.S.A in the summertime in the mid-1980s 4.The damage to the ozone layer was caused by ________. A. the changeable weather B. ozone-destroying chemicals C. chemicals from refrigerators D. chemicals from air conditioners
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There was in Washington a policeman who was known as the man who arrested the president. The_______ took place when the man was a green officer_______ at No. 1 Street. One evening, President Grant, who had been invited to a party of friends, was_______ home to meet the engagement. The _______, with its four horses, was running down the street so fast that the new policeman _______ the driver to stop. The driver _______ him and asked what was the _______. “Don’t you know you are driving about nine times as fast as the law _______?” said the officer. “Yes,” answered the president. “I suppose I was, _______ you speak of it.” “Well, then, you may __________yourself under arrest and go with me to the station house.” There were some marks from the other __________of the carriage __________ whom was a foreign minister, but the president said, “The man is __________ right.” and asked the policeman to __________himself behind him. __________ the policeman heard a soft voice, “I only thought you __________ know that it’s President.” The officer was very __________ and begged them to let him go, __________ the president would have none of it. When they reached the station, the captain turned __________. Apologies were made, but the president __________on paying the proper fine. 1.A. accident B. incident C. account D. affair 2.A. stood B. stationed C. kept watch D. defending 3.A. walking B. wandering C. running D. hurrying 4.A. car B. bus C. carriage D. train 5.A. begged B. hoped C. ordered D. suggested 6.A. agreed B. accepted C. listened D. obeyed 7.A. matter B. thing C. affair D. business 8.A. lets B. forbids C. tells D. allows 9.A. though B. unless C. while D. since 10.A. decide B. guess C. consider D. treat 11.A. passengers B. drivers C. officers D. policemen 12.A. with B. among C. in D. except 13.A. rather B. hardly C. rarely D. perfectly 14.A. seat B. sit C. stand D. climb 15.A. Fortunately B. Happily C. Suddenly D. Carefully 16.A. could B. must C. ought to D. may 17.A. excited B. interested C. moved D. astonished 18.A. therefore B. but C. and D. otherwise 19.A. white B. green C. red D. yellow 20.A. demanded B. asked C. required D. insisted
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He _____ his eyes from his desk and then ____ from his seat. A. rose, raised B. rose, rose C. raised, raised D. raised, rose
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There is a man _______ himself Mr Li waiting for you. A. called B. calls C. calling D. call
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The audience clapped their hands _____ to the music. A. in time B. on time C. at time D. behind time
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He ______ at once when I promised to help him. A. cheered up B. gave up C. lighted up D. turned up
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________ the books where they were ________. A. Lay, laying B. Lie, lying C. Lay, lying D. Lie, laying
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