西安电子科技大学
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The ____ of tests in the United States institutions can be a new and frightening experience for many foreign students.
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Many of the shopkeepers are poor. There isn’t much ____ in this town.
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机器人我们正生活在一个机器人承担许多工作的时代。机器人可以制造汽车、驾驶飞机和处理账单。不过这些机器人并不是人形机器。它们的外形并不像我们。它们是特别制造出来代替人做某些工作的机器，可以给它们以任何适宜的外形。机器人的“脑子”是一部电脑，它能够储存指令，并能够控制其他部件。机器人有手臂，能够做人用手干的多种工作。例如，机器人可以在汽车装配线上焊接车身和喷漆。使用机器人比使用工人的优越之处是它们可以不停地长时间工作，它们从不疲劳，而工作的准确性却始终如一。它们可以在人无法忍受的条件下工作，如有高温、有强烈的噪音或是有危险射线的场合，随着机器人数量的增加，它们的制造成本也会下降。尽管机器人正在迅速承担工业中的许多工作，但要在家里做家务活却似乎还差得很远。问题在于即使干一半的家务活也需要有一个非常复杂、非常昂贵的机器人。
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Why is the Native Language Learnt So Well?How does it happen that children learn their mother tongue so well? When we compare them with adults learning a foreign language, we often find this interesting fact a little child without knowledge or experience often succeeds in a complete mastery of the language. A grown-up person with fully developed mental powers, in most cases, may end up with a faulty and inexact command. What accounts for this difference?Despite other explanations, the real answer in my opinion lies partly in the child himself, partly in the behavior of the people around him. In the first place, the time of learning the mother tongue is the most favorable of all, namely, the first years of life. A child hears it spoken from morning till night and, what is more important, always in its genuine form, with the right pronunciation, right intonation, right use of words and right structure. He drinks in all the words and expressions which come to him in a fresh, ever-bubbling spring. There is no resistance: there is perfect assimilation.Then the child has, as it were, private lessons all the year round, while an adult language-student has each week a limited number of hours which he generally shares with others. The child has another advantage: he hears the language in all possible situations, always accompanied by the right kind of gestures and facial expressions. Here there is nothing unnatural, such as is often found in language lessons in schools, when one talks about ice and snow in June or scorching heat in January. And what a child hears is generally what immediately interests him. Again and again, when his attempts at speech are successful, his desires are understood and fulfilled.Finally, though a child’s “teachers” may not have been trained in language teaching, their relations with him are always close and personal. They take great pains to make their lessons easy.New Efforts to Lean about MarsTwo weeks ago, the United States launched a spaceship named Mars Global Surveyor. It is expected to arrive at Mars next September after traveling about 7 hundred million kilometers. It will orbit the planet. Its main task is to make the most detailed map of Mars. On December 2nd, the United States is to launch another spacecraft Mars Pathfinder. Although the two spacecrafts are not designed to search for life, they will seek out conditions that could support life.Mars is the fourth planet from the Sun the next beyond Earth. It has been a bright object of mystery in the night sky since ancient times. It is named for the Roman God of War. Because of the color of its soil and rocks, Mars is also called the red planet. If life, past or present, is to be found anywhere else in the solar system, scientists say, Mars is probably the space. They think Mars and Earth were similar as young planets. They believe that young Mars was much warmer and wetter than it is now; and had much thicker atmosphere. Today, Mars’ atmosphere is less than 1% as thick as Earth’s. It is mostly carbon dioxide while Earth’s atmosphere is mainly nitrogen. Mars is about half the size of Earth. It is almost 7,000 kilometers across. It has huge volcanoes and canyon 4,000 kilometers across, the biggest known in the solar system. Mars is also known for great dust storms which sometimes cover the planet. The average temperature on Mars is 53 degrees below zero Celsius. Mars’ warm atmosphere is 27 above zero.In some places the Martian surface looks like a desert on Earth. In others, it looks like the surface of our moon. By studying Mars, scientists say we can hope to learn more about the history and perhaps the future of our own planet. Surface on Mars that are almost 4,000 million years old show remains of ancient lakes. These suggest that that liquid water once flowed. Mars water is hidden under its surface now. Instruments on the spacecraft will search for it.Extinction Stalks World’s TigersUnless governments take significant measures to protect tigers, they may go extinct by 2010, the World Wildlife Fund said Thursday.The conservation group said tiger numbers have decreased 95 percent in the past century and only 5,000—7,200 tigers still survive in the wild—compared with nearly 10 times that many at the start of the century.WWF, published an update Feb. 11, 2019 of their study—Wanted Alive: Tigers in the Wild, marking the end of the Chinese Year of the Tiger.The report states that despite sustained efforts over the past year, much remains to be done to prevent the tiger from becoming extinct early next century. If governments do not crack down on poaching and eliminate the demand for tiger products, the tiger will be stalked to extinction, says WWF.“We cannot let up for one moment if we are to ensure that tigers will still exist in the wild by the next Chinese Year of the Tiger in 2010,” said Elizabeth Kemf, species conservation information manager at WWF International and one of the authors of the report.The group cites illegal hunting for the medicinal trade, loss of prey species weak law enforcement, poaching, habitat loss and a shrinking gene pool as the other major threats facing the world’s tiger population.The WWF said one major success during 1998 was the passage of legislation by the U.S. Congress banning the import and sale of any product claiming to contain ingredients made of rhinoceros—another endangered species—or tiger parts.In addition, WWF established a Tiger Emergency Fund, supported the Tiger Conservation Program in India, and worked in the Russian Far East.Three of the eight subspecies of tiger—the Bali, Caspian and Javan tigers are extinct. The South China tiger faces the same facts as only 20 or 30 are known to remain in the wild, down from an estimated 4, 000 in the 1950s.
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There are some earth phenomena you can count on, but the magnetic field, someday is not of them. It fluctuates in strength, drifts from its axis, and every few 100,000 years undergo, dramatic polarity reversal—a period when north pole becomes south pole and south pole becomes north pole. But how is the field generated, and why is it so unstable?Groundbreaking research by two French geophysicists promises to shed some light on the mystery. Using 80 meters of deep sea sediment (沉淀物) core, they have obtained measurements of magnetic-field intensity that span 11 polarity reversals and four million years. The analysis reveals that intensity appears to fluctuate with a clear, well-defined rhythm. Although the strength of the magnetic field varies irregularly during the short term, there seems to be an inevitable long term decline preceding each polarity reversal. When the poles flip—a process that takes several hundred thousand years—the magnetic field rapidly regains its strength and the cycle is repeated.The results have caused a stir among geophysicists. The magnetic field is thought to originate from molten (熔化的) iron in the outer core, 3,000 kilometers beneath the earth’s surface. By studying mineral grains found in material ranging from rocks to clay articles, previous researchers have already been able to identify reversals dating back 170 million years, including the most recent switch 730,000 years ago. How and why they occur, however, has been widely debated. Several theories link polarity flips to external disasters such as meteor impacts. But Peter Olson, a geophysicist at the Johns Hopkins University in Baltimore, says this is unlikely if the French researchers are right. In fact, Olson says intensity that predictably declines from one reversal to the next contradicts 90 percent of the models currently under study. If the results prove to be valid, geophysicists will have a new theory to guide them in their quest to understand the earth’s inner physics. It certainly points the direction for future research.1. Which of the following titles is most appropriate to the passage?2. The word “flip” (Para. 2) most probably means ____.3. What have the two French geophysicists discovered in their research?4. The French geophysicists’ study is different from currently prevailing theories in ____.5. In Peter Olson’s opinion the French experiment ____.
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