题目内容
The human ear contains the organ for hearing and the organ for balance. Both organs involve fluid-filled channels containing hair cells that produce electrochemical impulses when the hairs are stimulated by moving fluid. The ear can be divided into three regions: outer, middle, and inner. The outer ear collects sound waves and directs them to the eardrum separating the outer ear from the middle ear. The middle ear conducts sound vibrations through three small bones to the inner ear. The inner ear is a network of channels containing fluid that moves in response to sound or movement. To perform the function of hearing, the ear converts the energy of pressure waves moving through the air into nerve impulses that me brain perceives as sound. Vibrating objects, such as the vocal cords of a speaking person, create waves in me surrounding air. These waves cause the eardrum to vibrate with the same frequency. The three bones of the middle ear amplify and transmit the vibrations to the oval window, a membrane on the surface of the cochlea, the organ of hearing. Vibrations of me oval window produce pressure waves in the fluid inside me cochlea. Hair cells in the cochlea convert the energy of the vibrating fluid into impulses that travel along the auditory nerve to the brain. The organ for balance is also located in the inner ear. Sensations related to body position are generated much like sensations of sound. Hair cells in the inner ear respond to changes in head position with respect to gravity and movement. Gravity is always pulling down on the hairs, sending a constant series of impulses to the brain. When the position of the head changes—as when the head bends forward—the force on the hair cells changes its output of nerve impulses. The brain then interprets these changes to determine the head’s new position. In this passage, the author mainly explains______.
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Our culture has caused most Americans to assume not only that our language is universal but that the gestures we use are understood by everyone. We do not realize that waving good-bye is the way to summon a person from the Philippines to one’s side, or that in Italy and some Latin-American countries, curling the finger to oneself is a sign of farewell. Those private citizens who sent packages to our troops occupying Germany after World War II and marked them GIFT to escape duty payments did not bother to find out that " Gift" means poison in German. Moreover, we like to think of ourselves as friendly, yet we prefer to be at least 3 feet or an arm’s length away from others. Latins and Middle Easterners like to come closer and touch, which makes Americans uncomfortable. Our linguistic and cultural blindness and the casualness with which we take notice of the developed tastes, gestures, customs and languages of other countries, are making us lose friends, business and respect in the world. Even here in the United States, we make few concessions to the needs of foreign visitors. There are no information signs in four languages on our public buildings or monuments; we do not have multilingual guided tours. Very few restaurant menus have translations, and multilingual waiters, bank clerks and policemen are rare. Our transportation systems have maps in English only and often we ourselves have difficulty understanding them. When we go abroad, we tend to cluster in hotels and restaurants where English is spoken. Then attitudes and information we pick up are conditioned by those natives—usually the richer—who speak English. Our business dealings, as well as the nation’s diplomacy, are conducted through interpreters. For many years, America and Americans could get by with cultural blindness and linguistic ignorance. After all America is the most powerful country of the free world, the distributor needed funds and goods. But all that is past. American dollars no longer buy all good things, and we are slowly beginning to realize that our proper role in the world is changing. A 1979 Harris poll reported that 55 percent of Americans want this country to play a more significant role in world affairs; we want to have a hand in the important decisions of the next century, even though it may not always be the upper hand. According to the author, Americans’ cultural blindness and linguistic ignorance will______.
Pity those who aspire to put the initials PhD after their names. After 16 years of closely supervised education, prospective doctors of philosophy are left more or less alone to write the equivalent of a large book. Most social-science postgraduates have still not completed their theses by the time their grant runs out after three years. They must then get a job and finish in their spare time, which can often take a further three years. By then, most new doctors are sick to death of the narrowly defined subject which has blighted their holidays and ruined their evenings. The Economic and Social Research Council, which gives grants to postgraduate social scientists, wants to get better value for money by cutting short this agony. It would like to see faster completion rates; until recently, only about 25% of PhD candidates were finishing within four years. The ESRC’s response has been to stop PhD grants to all institutions where the proportion taking less than four years is below 10% ; in the first year of this policy the national average shot up to 39%. The ESRC feels vindicated in its toughness, and will progressively raise the threshold to 40% in two years. Unless completion rates improve further, this would exclude 55 out of 73 universities and polytechnics — including Oxford University, the London School of Economics and the London Business School. Predictably, howls of protest have come from the universities, who view the blacklisting of whole institutions as arbitrary and negative. They point out that many of the best students go quickly into jobs where they can apply their research skills, but consequently take longer to finis their theses. Polytechnics with as few as two PhD candidates complain that they are penalized by random fluctuations in student performance. The colleges say there is no hard evidence to prove that faster completion rates result from greater efficiency rather than lower standards or less ambitious doctoral topics. The ESRC thinks it might not be a bad thing if PhD students were more modest in their aims. It would prefer to see more systematic teaching of research skills and fewer unrealistic expectations placed on young men and women who are undertaking their first piece of serious research. So in future its grants will be given only where it is convinced that students are being trained as researchers, rather than carrying out purely knowledge-based studies. The ESRC can not dictate the standard of thesis required by external examiners, or force departments to give graduates more teaching time. The most it can do is to try to persuade universities to change their ways. Recalcitrant professors should note that students want more research training and a less elaborate style of thesis, too. All the following statements are the arguments against ESRC’s policy EXCEPT______.
Pity those who aspire to put the initials PhD after their names. After 16 years of closely supervised education, prospective doctors of philosophy are left more or less alone to write the equivalent of a large book. Most social-science postgraduates have still not completed their theses by the time their grant runs out after three years. They must then get a job and finish in their spare time, which can often take a further three years. By then, most new doctors are sick to death of the narrowly defined subject which has blighted their holidays and ruined their evenings. The Economic and Social Research Council, which gives grants to postgraduate social scientists, wants to get better value for money by cutting short this agony. It would like to see faster completion rates; until recently, only about 25% of PhD candidates were finishing within four years. The ESRC’s response has been to stop PhD grants to all institutions where the proportion taking less than four years is below 10% ; in the first year of this policy the national average shot up to 39%. The ESRC feels vindicated in its toughness, and will progressively raise the threshold to 40% in two years. Unless completion rates improve further, this would exclude 55 out of 73 universities and polytechnics — including Oxford University, the London School of Economics and the London Business School. Predictably, howls of protest have come from the universities, who view the blacklisting of whole institutions as arbitrary and negative. They point out that many of the best students go quickly into jobs where they can apply their research skills, but consequently take longer to finis their theses. Polytechnics with as few as two PhD candidates complain that they are penalized by random fluctuations in student performance. The colleges say there is no hard evidence to prove that faster completion rates result from greater efficiency rather than lower standards or less ambitious doctoral topics. The ESRC thinks it might not be a bad thing if PhD students were more modest in their aims. It would prefer to see more systematic teaching of research skills and fewer unrealistic expectations placed on young men and women who are undertaking their first piece of serious research. So in future its grants will be given only where it is convinced that students are being trained as researchers, rather than carrying out purely knowledge-based studies. The ESRC can not dictate the standard of thesis required by external examiners, or force departments to give graduates more teaching time. The most it can do is to try to persuade universities to change their ways. Recalcitrant professors should note that students want more research training and a less elaborate style of thesis, too. The ESRC would prefer______.
Scientists have long understood that supermassive black holes weighing millions or billions of suns can tear apart stars that come too close. The black hotels gravity pulls harder on the nearest part of the star, an imbalance that pulls the star apart over a period of minutes or hours, once it gets close enough. Scientists say this uneven pulling is not the only hazard facing the star. The strain of these unbalanced forces can also trigger a nuclear explosion powerful enough to destroy the star from within. Matthieu Brassart and Jean-Pierre Luminet of the Observatoire de Paris in Meudon, France, carried out computer simulations of the final moments of such an unfortunate star’s life, as it veered towards a supermassive black hole. When the star gets close enough, the uneven forces flatten it into a pancake shape. Some previous studies had suggested this flattening would increase the density and temperature inside the star enough to trigger intense nuclear reactions that would tear it apart. But other studies had suggested that the picture would be complicated by shock waves generated during the flattening process and that no nuclear explosion should occur. The new simulations investigated the effects of shock waves in detail, and found that even when their effects are included, the conditions favor a nuclear explosion. " There will be an explosion of the star — it will be completely destroyed," Brassart says. Although the explosion obliterates the star, it saves some of the star’s matter from being devoured by the black hole. The explosion is powerful enough to hurl much of the star’s matter out of the black hole’s reach, he says. The devouring of stars by black holes may already have been observed, although at a much later stage. It is thought mat several months after the event that rips the star apart, its matter starts swirling into the hole itself. It heats up as it does so, releasing ultraviolet light and X-rays. If stars disrupted near black holes really do explode, then they could in principle allow these events to be detected at a much earlier stage, says Jules Hatpern of Columbia University in New York, US2. "It may make it possible to see the disruption of that star immediately if it gets hot enough," he says. Brassart agrees. "Perhaps it can be observed in the X-rays and gamma rays, but it’s something that needs to be more studied," he says. Supernova researcher Chris Fryer of the Los Alamos National Laboratory in Los Alamos, New Mexico, US3, says the deaths of these stars are difficult to simulate, and he is not sure whether the researchers have proven their case that they explode in the process. According to the fourth paragraph, which of the following is NOT true
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