大学英语四级

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大学英语四级大学英语六级大学英语三级专四专八成人英语三级商务英语雅思 GRE

In August, environmentalists in the Philippines vandalized (肆意破坏 ) a field of Golden Rice, an experimental grain whose genes had been modified. Its seeds will be handed out free to farmers. The aim is to improve the health of children in poor countries by reducing vitamin A deficiency, which contributes to hundreds of thousands of premature deaths and cases of blindness each year. Environmentalists claim that these sorts of actions are justified because genetically modified crops pose health risks.Now the main ground for those claims has crumbled. Last year a paper which was published in a respected journal found that unusual rates of tumours and deaths in rats that had been fed upon a variety of genetic modification(GM) (转基因) corn.Other studies found no such effects. But this one enabled campaigners to make a health-and-safety argument against GM crops--one persuasive enough to influence governments. After the study appeared, Russia suspended imports of the grain in question. Kenya banned all GM crops. And the French prime minister said that if the results were confirmed he would press for a Europe-wide ban on the GM corn. There is now no serious scientific evidence that GM crops do any harm to the health of human beings. There is plenty of evidence, though, that they benefit the health of the planet. One of the biggest challenges facing mankind is to feed the 9 billion-10 billion people who will be alive and richer in 2050. This will require doubling food production on roughly the same area of land, using less water and fewer chemicals. It will also mean making food crops more resistant to the droughts and floods that seem likely if climate change is as bad as scientists fear. If the Green revolution had never happened, and yields had stayed at 1960 levels, the world could not produce its current food output even if it ploughed up every last acre of cultivable land.In contrast, GM crops boost yields, protecting wild habitat from the plough.They are more resistant to the vagaries of climate change, and to diseases and pests, reducing the need for agrochemicals. Genetic research holds out the possibility of breakthroughs that could vastly increase the productivity off arming. Vandalizing GM field trials is a bit like the campaign of somereligious leaders to prevent smallpox inoculations: it causes misery, even death, in the name of unscientific belief. 答案解析
According to sociologists, there are several different ways in which a person may become recognized as the leader of a social group. In the family, traditional cultural patterns confer leadership on one or both of the parents. In other cases, such as friendship groups, one or more persons may gradually emerge as leaders, although there is no formal process of selection. In larger groups, leaders are usually chosen formally through election or recruitment. Although leaders are often thought to be people with unusual personal ability, decades of research have failed to produce consistent evidence that there is any category of "natural leaders". It seems that there is no set of personal qualities that all leaders have in common; rather, virtually any person may be recognized as a leader if the person has qualities that meet the needs of that particular group. Research suggests that there are typically two different leadership roles that are held by different individuals. Instrumental leadership is leadership that emphasizes the completion of tasks by a social group. Group members look to instrumental leaders to" get things done". Expressive leadership, on the other hand, is leadership that emphasizes the collective well-beings of a social group's members. Expressive leaders are less concerned with the overall goals of the group than with providing emotional support to group members and attempting to minimize tension and conflict among them. Instrumental leaders are likely to have a rather secondary relationship to other group members. They give others and may discipline group members whoinhibit (阻碍) attainment of the group's goals. Expressive leaders cultivate a more personal or primary relationship to others in the group. They offer sympathy when someone experiences difficulties and try to resolve issues that threaten to divide the group. As the difference in these two roles suggest,expressive leaders generally receive more personal affection from groupmembers; instrumental leaders, if they are successful in promoting group goals,may enjoy a more distant respect. 答案解析
One of the world's first video games,Tetris(俄罗斯方块 ), has turned thirty years old, and its brand is anything but old school.But what's kept people swiping and clicking to ensure each row of blocks stays aligned and disappears into the virtual world since its development in 1984 Soviet Russia? A combination of new plat form sand an attracting psychological appeal. Maya Rogers, the CEO of Blue Planet Software, the sole agent of the Tetris brand, said the protection of the game'score over the last three decades has aided its longevity. As mobile and social become two of the largest sources for gaming these days, Tetris isn't showing any signs of losing its appeal. Currently appearing on over 50 different gaming platforms, from the 1983 Nintendo Entertainment System (NES) to smart phones,Tetris is sold on over 425 million mobile devices. More than 20 billion games of Tetris Battle have been played on Facebook, too. There's some thing psychologically entrancing about the game, that's kept people hooked through the years. "Play a game of Tetris," said Rogers, "and satisfy your craving to create order out of chaos." Plus, there's the added quality of playing Tetris and never feeling wholly fulfilled."There' s no correct move that you can make," said. Neubauer, a loyal player of the game who work as a senior analyst at Saibus Research, an independent research and advisory firm, "The quest for the perfect move never ends." Tom Stafford, a professor of cognitive development and psychology at Sheffield University in the U.K., says that Tetris has been around so long because it transports garners into a different realm when they play. "It's a world of perpetually generating uncompleted tasks," he said. As he's said in the past, too, "Tetris is the granddaddy of puzzle games like Candy Crush saga--the things that keep us puzzling away for hours, days and weeks.""Tetris is pure game: thereis no benefit to it, nothing to leam, no social or physical consequence,"he added. "It is almost completely pointless, but keeps us coming back for more." 答案解析
If you want to teach your children howto say sorry, you must be good at saying it yourself, especially to your own children. But how you say it can be quite tricky.If you say to your children "I'm sorry I got angry with you, but ..." what follows that "but" can render the apology ineffective: "I had a bad day" or "your noise was giving me a headache" leaves the person who has been injured feeling that he should be apologizing for his bad behavior in expecting an apology. Another method by which people appear to apologize without actually doing so is to say "I'm sorry you're upset"; this suggests that you are somehow at fault for allowing your self to get upset by what the other person has done. Then there is the general, all covering apology, which avoids the necessity of identifying a specific act that was particularly hurtful or insulting, and which the person who is apologizing should promise never to do again. Saying "I'm useless as a parent"does not commit a person to any specific improvement. These pseudo-apologies are used by people who believe saying sorry shows weakness, Parents who wish to teach their children to apologize should see it as a sign of strength, and there forenot resort to these pseudo-apologies. But even when presented with examples of genuine contrition, children still need help to be-come aware of the complexities of saying sorry. A three-year-old might need help in under standing that other children feel pain just as he does, and that hitting a playmate over the head with a heavy toy requires an apology. A six-year-old might need reminding that spoiling other children' s expectations can require an apology.A 12-year-old might need to be shown that raiding the biscuit tin with-out asking permission is acceptable, but that borrowing a parent' s clothes without permission is not. 答案解析
If you want to teach your children howto say sorry, you must be good at saying it yourself, especially to your own children. But how you say it can be quite tricky.If you say to your children "I'm sorry I got angry with you, but ..." what follows that "but" can render the apology ineffective: "I had a bad day" or "your noise was giving me a headache" leaves the person who has been injured feeling that he should be apologizing for his bad behavior in expecting an apology. Another method by which people appear to apologize without actually doing so is to say "I'm sorry you're upset"; this suggests that you are somehow at fault for allowing your self to get upset by what the other person has done. Then there is the general, all covering apology, which avoids the necessity of identifying a specific act that was particularly hurtful or insulting, and which the person who is apologizing should promise never to do again. Saying "I'm useless as a parent"does not commit a person to any specific improvement. These pseudo-apologies are used by people who believe saying sorry shows weakness, Parents who wish to teach their children to apologize should see it as a sign of strength, and there forenot resort to these pseudo-apologies. But even when presented with examples of genuine contrition, children still need help to be-come aware of the complexities of saying sorry. A three-year-old might need help in under standing that other children feel pain just as he does, and that hitting a playmate over the head with a heavy toy requires an apology. A six-year-old might need reminding that spoiling other children' s expectations can require an apology.A 12-year-old might need to be shown that raiding the biscuit tin with-out asking permission is acceptable, but that borrowing a parent' s clothes without permission is not. 答案解析
胸段脊髓半切综合征（Brown－Sequard）的运动障碍表现为答案解析
Long after the 1998 World Cup was won, disappointed fans were still cursing the disputed refereeing(裁判)decisions that denied victory to their team. A researcher was appointed to study the performance of some top referees.　　The researcher organized an experimental tournament(锦标赛)involving four youth teams. Each match lasted an hour, divided into three periods of 20 minutes during which different referees were in charge.　　Observers noted down the referees’errors, of which there were 61 over the tournament. Converted to a standard match of 90 minutes, each referee made almost 23 mistakes, a remarkably high number.　　The researcher then studied the videotapes to analyze the matches in detail. Surprisingly, he found that errors were more likely when the referees were close to the incident. When the officials got it right, theywere, on average, 17 meters away from the action. The average distance in the case of errors was12 meters.The research shows the optimum(最佳的)distance is about 20 meters.　　There also seemed to be an optimum speed. Correct decisions came when the referees were moving at a speed of about 2 meters per second. The average speed for errors was 4 meters per second.　　If FIFA, football’s international ruling body, wants to improve the standard of refereeing at the next World Cup, it should encourage referees to keep their eyes on the action from a distance, rather than rushing to keep up with the ball, the researcher argues.　　He also says that FIFA’s insistence that referees should retire at age 45 may be misguided. If keeping upwith the action is not so important, their physical condition is less critical. 答案解析
2月14日，某投资者开户后在其保证金账户中存人保证金10万元，开仓卖出豆粕期货合约40手，成交价为3120元/吨；其后将合约平仓15手，成交价格为3040元/吨，当日收盘价格为3055元/吨，结算价为3065元/吨。期货公司向该投资者收取的豆粕期货合约保证金比例为6%。(交易费用不计)该投资者的当日盈亏为（　）元。答案解析
该客户当日交易保证金为（　）元。答案解析
下列关于我国期货交易所集合竞价的说法正确的是（　）。答案解析
同时买入和卖出（）种或（）种以上期货合约的指令称为套利指令。答案解析
结算时，交易所将会员的手续费、税金等各项费用从会员的（　）中直接扣划。答案解析
某交易者以3780元/吨卖出10手白糖期货合约，之后以3890元/吨的价格全部平仓，这笔交易（　）元。(不计手续费等费用) 答案解析
U. S. Education Secretary Arne Duncan appealed Friday for a new generation of extraordinary teachers，calling education the civil rights cause of our time. Duncan told about 100 prospective（未来的）teachers at the University of Virginia that veterans，retirees and professionals seeking a second career must pay attention to the call to teach. He said the need is especially acute for black men in the nation’s classrooms. The Virginia address is the first of several Duncan will make in October to press for bright candidates to enter teaching. He’ll host a virtual town meeting with teachers from around the nation oil Oct. 20，then deliver a major address on teacher preparation two days later in New York City. Duncan stressed the importance of teaching as the U. S. competes with an increasingly educated global work force，saying strong education is needed to reduce dropout rates among African-American，Latino and low-income students. “I believe that education is the civil rights issue of our generation，”Duncan said. “If you care about promoting opportunity and reducing inequality and social injustice，the classroom is the place to start. ” Duncan noted that the next four years alone could see one-third of the nation’s teachers and administrators leave. The departure of veteran educators will create huge demand for new teachers--200，000 annually in good economic times，he said. Duncan stressed that the demand for teachers is greatest amon9“high-poverty，high-needs” and rural schools, as well as in subjects such as math and science. “It is especially troubling，”he added，“that less than 2 percent of our nation’s teachers are African-American males. ” Duncan said the way to bring more young black men into the teaching profession is to make sure that they continue their studies and don’t drop out at the high rates they do IIOW. “0ur African male dropout rate is too high. If you’re dropping out of high school you can’t be a teacher,” he said. Duncan said the nation cannot rely alone oil schools of education to produce the next generation of teachers. He called for expanding alternatives such as Teach for America which recruits recent college graduates to teach in schools in poor communities for at least two years. 答案解析
It happens to every medical student sooner or later. You get a cough that persists for a while. Ordinarily,you would just ignore it--but now, armed with your rapidly growing medical knowledge, you can’t help worrying. The cough could mean just a cold, but it could also be a sign of lung cancer.　　For doctors in training, nurses and medical journalists, hypochondria is an occupational danger. The feeling usually passes after a while, leaving only a funny story to tell at a dinner party. But for the tens ofthousands who suffer from true hypochondria they live in constant terror that they are dying of some awfuldisease, or even several awful diseases at once. Doctors can assure them that there’s nothing wrong, but since the cough is real, the assurances fall on deaf ears. And because no physician or test can offer a 100% guarantee that one doesn’t have cancer, a hypochondriac always has fuel to feed Iris .or her worst fears.　　Hypochondriacs don’t harm just themselves; they block the whole healthcare system. Although they account for only about 6% of the patients who visit doctors every year, they tend to burden their physicians with frequent visits that take up excessive amounts of time. And the problem may be worse, thanks to the popularity of medical information on the Internet. They go on the Web and learn about new diseases and new presentations of old diseases that they never even knew about before. Doctors have taken to calling this phenomenon cyberchondria (网络疑病症). 答案解析
该食糖购销企业套期保值结束后每吨（　）。答案解析
Not all sounds made by animals serve as language, and we have only to turn to that extraordinary discovery of echolocation (回声定位) in bats to see a case in which the voice plays a strictly practical role.　　To get a full appreciation of what this means we must turn first to some recent human inventions. Everyoneknows that if he shouts near a wall or a mountainside, an echo will come back. The further off this solid obstacle, the longer time it will take for the return of the echo. A sound made by tapping on the main body of a ship will be reflected from the sea bottom, and by measuring the time interval between the taps andthe receipt of the echoes the depth of the sea at that point can be calculated. So was born the echo-sounding equipment, now in general use in ships. Every solid object will reflect a sound, varying according to the size and nature of the object. A shoal of fish will do this. So it is a comparatively simple step fromlocating the sea bottom to locating a shoal of fish. With experience, and with improved equipment, it is now possible not only to locate fish but to tell if it is herring, cod, or other well-known fish, by the pattern of its echo.　　A few years ago it was found that certain bats emit squeaks (吱吱声) and by receiving ’he echoes they could locate and steer clear of obstacles--or locate flying insects on which they feed. This echolocation in bats is often compared with radar, the principle of which is similar. 答案解析
A remarkable variety of insects live in this planet More species of insects exist than all other animal species together. Insects have survived on earth for more than 300 million years, and may possess the ability to survive for millions more.　　Insects can be found almost everywhere -- on the highest mountains and on the bottom of rushing streams, in the cold South Pole and in bubbling hot springs. They dig through the ground, jump and sing in the trees,and run and dance in the air. They come in many different colors and various shapes. Insects are extremely useful to humans, pollinating (授粉)our crops as well as flowers in meadows, forests, deserts and otherareas. But licks and some insects, such as mosquitoes and fleas, can transmit disease.　　There are many reasons why insects are so successful at surviving. Their amazing ability to adapt permits them to live in extreme ranges of temperatures and environments. The one place they have not yet been found to any major extent is in the open oceans. Insects can survive on a wide range, of natural and artificial foods—paint, pepper, glue, books, grain, cotton，other insects, plants and animals Because they are small they can hide in tiny spaces.　　A strong, hard but flexible shell covers their soft organs and is resistant to chemicals, water and physical impact. Their wings give them the option of flying away from dangerous situations or toward food or males. Also, insects have an enormous reproductive capacity: An African ant queen can lay as many as 43,000 eggs a day.　　Another reason for their success is the strategy of protective color. An insect may be right before our eyes, but nearly invisible because it is cleverly disguised like a green leaf, lump of brown soil, gray lichen (青苔),a seed or some other natural object Some insects use bright, bold colors to send warning signalsthat they taste bad,sting or are poison.Others have wing patterns that look like the eyes of a huge predator, bitter-tasting insects; hungry enemies are fooled into avoiding them. 答案解析
5月8日，某套期保值者以2270元／吨在9月份玉米期货合约上建仓，此时玉米现货市场价格为2100元／吨，则此时玉米基差为（　）元／吨。答案解析
A subject which seems to have been insufficiently studied by doctors and psychologists is the influence ofgeography and climate on the psychological and physical health of mankind.There seems no doubt that the general character of the landscape, the relative length of day and night, and the climate must all play a big part in determining what kind of people we are.　　It is true that a few studies have been made. Where all the inhabitants of a particular area enjoy exceptionally good or bad health, scientists have identified .contributory factors such as the presence or absence of substances like iodine, fluoride, calcium, or iron in the water supply, or perhaps types of land thatprovide breeding places for pests like mosquitoes or rats.　　Moreover, we can all generalize about types of people we have met. Those living in countries .with long dark winters are apt to be less talkative and less vivacious than inhabitants of countries where the climateis more equable(稳定的). And where the olive and the orange grow, there the inhabitants are cheerful, talkative, and spontaneous.　　But these commonplace generalizations are inadequate: the influence: of climate and geography should be studied in depth. Do all mountain dwellers live to a ripe old age? Does the drinking of wine, rather than beer, result in a sunny and open temperament? Is the strength and height of one of the Kenyan tribes due to their habitual drinking of the blood of cows?　　We are not yet sure of the answers to such .questions, but let us hope that something of benefit to mankind may eventually result from such studies. 答案解析