单选题Eat More, Weigh Less, Live Longer Clever genetic detective work may have found out the reason why a near-starvation diet prolongs the life of many animals. Ronald Kahn at Harvard Medical School in Boston, US, and his colleagues have been able to extend the lifespan (寿命) of mice by 18 percent by blocking the rodent's (啮齿动物) increase of fat in specific cells. This suggests that thinness-and not necessarily diet-promotes long life in "calorie (热量单位，卡) restricted" animals. "It's very cool work," says aging researcher Cynthia Kenyon of the University of California, San Francisco. "These mice eat all they want, lose weight and live longer. It's like heaven. " Calorie restriction dramatically extends the lifespan of organisms as different as worms and rodents. Whether this works in humans is still unknown, partly because few people are willing to submit to such a strict diet. But many researchers hope they will be able to trigger the same effect with a drug once they understand how less food leads to a longer life. One theory is that eating less reduces the increase of harmful things that can damage cells. But Kahn's team wondered whether the animals simply benefit by becoming thin. To find out, they used biology tricks to disrupt the insulin (胰岛素) receptor (受体) gene in lab mice—but only in their fat cells. "Since insulin is needed to help fat cells store fat, these animals were protected against becoming fat," explains Kahn. This slight genetic change in a single tissue had dramatic effects. By three months of age, Kahn's modified mice had up to 70 percent less body fat than normal control mice, despite the fact that they ate 55 percent more food per gram of body weight. In addition, their lifespan increased. The average control mouse lived 753 days, while the thin rodents averaged a lifespan of 887 days. After three years, all the control mice had died, but one-quarter of the modified rodents were still alive. "That they get these effects by just manipulating the fat cells is controversial, "says Leonard Guarente of the Massachusetts Institute of Technology, who studies calorie restriction and aging. But Guarente says Kahn has yet to prove that the same effect is responsible for increased lifespan in calorie restricted animals. "It might be the same effect or there might be two routes to long life," he points out, "and that would be very interesting./

单选题The teacher couldn't tolerate the boy's bad behaviour any longer. A. put up B. put out C. put up with D. put off

单选题Jean has made up her mind not to go to the meeting.A. triedB. promisedC. decidedD. attempted

单选题Thousands of people perished in the storm.

单选题下面有3篇短文，每篇短文后有5道题，每题后面有4个选项。请仔细阅读短文并根据短文回答其后面的问题，从4个选项中选择1个最佳答案。{{B}}第一篇{{/B}} Awareness of earthquake hazards is now well developed in many countries, and the U. S. Geological Survey has recently published a map showing the relative probability of earthquake activity for various areas in the United States. The major hazard represented by seismic events along the great earthquake belts of the world has now been clearly recognized, and a great deal of research money and effort is being directed toward earthquake prediction and possible control. Active fault systems, such as the San Andreas fault in California, are carefully monitored for observable changes that could indicate an impending earthquake. Although the nature of earthquakes and earthquake belts are rela tively well understood, the possibility of accurately predicting major earthquakes, much less controlling them, still appears remote. Probably the most intriguing development in this field relates to the Rocky Mountain Arsenal earthquakes near Denver, Colorado. In 1962 injection of fluid wastes into the Precambrian basement rocks nearly 4000m below the ground surface was followed by a series of small earthquakes. Studies of this phenomenon have indicated that the injected fluid lubricated a fault zone under stress and thereby promoted release of seismic energy. Experimentation at the site is still going on, but the connection between the fluid injection and earthquake activity was quickly rea lized. Accordingly, the suggestion has been made that potentially destructive earthquakes could be converted into numerous nondestructive minor earthquakes by using fluid injection techniques. Thus, although man has no hope whatever of controlling the major earth movements that lead to earthquakes, he may in some cases be able to influence the manner in which earthquake energy is dissipated.

单选题Poor health and lack of money may both be to educational progress roadblocks .

单选题In order to survive man needs to consume food and water.A. workB. playC. liveD. walk

单选题Our aim was to {{U}}update{{/U}} the health service, and we succeeded. A. offer B. modernize C. provide D. fund

单选题{{B}}第三篇{{/B}} {{B}} Natural Medicines{{/B}} Since earliest days, humans have used some kinds of medicines. We know this because humans have survived. Ancient treatments for injury and disease were successful enough to keep humans from dying out completely. They were successful long before the time of modern medicine. Before the time of doctors with white coats and shiny(发亮的)instruments. Before the time of big hospitals with strange and wonderful equipment. Many parts of the world still do not have university-educated doctors, Nor do they have expensive hospitals. Yet injuries are treated. And diseases are often cured. How? By ancient methods. By medicines that might seem mysterious, even magical(有魔力的). Traditional medicines are neither mysterious nor magical, however. Through the centuries, tribal (部族的)medicine men experimented with plants. They found many useful chemicals in the plants. And scientists believe many of these traditional medicines may provide the cure for some of today's most serious diseases. Experts say almost 80% of the people in the world use plants for health care. These natural medicines are used not just because people have no other form of treatment. They are used because people trust them. In developed areas, few people think about the source of the medicines they buy in a store. Yet many widely used medicines are from ancient sources, especially plants. Some experts say more than 25% of modern medicines come, in one way or another, from nature. Scientists have long known that nature is really a chemical factory. All living things contain chemicals that help them survive. So scientists' interest in traditional medicine is not new. But it has become an urgent concern. This is because the earth's supply of natural medicines may be dropping rapidly.

单选题The volcanic eruption of Mount Pinatubo in 1991 blew a Ugigantic/U amount of sulfates into the stratosphere.

单选题She only needs a U minute /U amount of money

单选题It's impolite to {{U}}cut in{{/U}} when two persons are holding a conversation,

单选题The decision to invade provoked storms of protest.

单选题Have you talked to her {{U}}lately{{/U}}? A. lastly B. finally C. shortly D. recently

单选题 Batteries Built by Viruses What do chicken pox, the common cold, the flu, and AIDS have in common? They're all disease caused by viruses, tiny microorganisms that can pass from person to person. It's no wonder that when most people think about viruses, finding ways to steer clear of viruses is what's on people's minds. Not everyone runs from the tiny disease carriers, though. In Cambridge, Massachusetts, scientists have discovered that some viruses can be helpful in an unusual way. They are putting viruses to work, teaching them to build some of the world's smallest rechargeable batteries. Viruses and batteries may seem like an unusual pair, but they're not so strange for engineer Angela Belcher, who first came up with the idea. At the Massachusetts Institute of Technology (MIT) in Cambridge, she and her collaborators bring together different areas of science in new ways. In the case of the virus-built batteries, the scientists combine what they know about biology, technology and production techniques. Belcher's team includes Paula Hammond, who helps put together the tiny batteries, and Yet-Ming Chiang, an expert on how to store energy in the form of a battery. "We're working on things we traditionally don't associate with nature," says Hammond. Many batteries are already pretty small. You can hold A, C and D batteries in your hand. The coin-like batteries that power watches are often smaller than a penny. However, every year, new electronic devices like personal music players or ceil phones get smaller than the year before. As these devices shrink, ordinary batteries won't be small enough to fit inside. The ideal battery will store a lot of energy in a small package. Right now, Belcher's model battery, a metallic disk completely built by viruses, looks like a regular watch battery. But inside, its components are very small—so tiny you can only see them with a powerful microscope. How small are these battery parts? To get some ideas of the size, pluck one hair from your head. Place your hair on a piece of white paper and try to see how wide your hair is—pretty thin, right? Although the width of each person's hair is a bit different, you could probably fit about 10 of these virus-built battery parts, side to side, across one hair. These microbatteries may change the way we look at viruses.

单选题The ice is not thick enough to bear the weight of a tank. A．suffer B．accept C．receive D．support

单选题The new dentist is much better than his Upredecessor/U.

单选题The Cold Places The Arctic is a polar region. It surrounds the North Pole. Like Antarctica, the Arctic is a land of ice and snow. Antarctica holds the record for a low temperature reading—125 degrees Fahrenheit below zero. Reading of 85 degrees below zero is common in both the Arctic and Antarctica. Winter temperatures average 30 degrees below zero in the Arctic. At the South Pole the winter average is about 73 degrees below zero. One thing alone makes it almost impossible for men to live in Antarctica and in parts of the Arctic. This one thing is the low temperature—the killing chill of far North and the polar South. To survive, men must wear the warmest possible clothing. They must build windproof shelters. They must keep heaters going at all times. Not ever for a moment can they be unprotected against the below-zero temperatures. Men have a way of providing for themselves. Polar explorers wrap themselves in warm coats and furs. The cold makes life difficult. But the explorers can stay alive. What about animals? Can they survive? Do we find plants? Do we find life in the Arctic and in Antarctica? Yes, we do. There is life in the oceans. There is life on land. Antarctica, as we have seen, is a cold place indeed. But this has not always been the case. Expedition scientists have discovered that Antarctica has not always been a frozen continent. At one time the weather in Antarctica may have much like our own. Explorers have discovered coal in Antarctica. This leads them to believe that Antarctica at one time was a land of swamps and forests. Heat and moisture must have kept the trees in the forests alive.

单选题 Benefited or Hurt For the most part, it seems, workers in rich countries have little to fear from globalization, and a lot to gain. But is the same thing true for workers in poor countries? The answer is that they are even more likely than their rich country counterparts to benefit, because they have less to lose and more to gain. Orthodox economics takes an optimistic line on integration and the developing countries. Openness to foreign trade and investment should encourage capital to flow to poor economies. In the developing world, capital is scarce, so the returns on investment there should be higher than in the industrialized countries, where the best opportunities to make money by adding capital to labor have already been used up. If pool countries lower their barriers to trade and investment, the theory goes: rich foreigners will want to send over some of their capital. If this inflow of resources arrives in the form of loans or portfolio investment, it will supplement domestic savings and loosen the financial constraint on additional investment by local companies. If it arrives in the form of new foreign controlled operations, FDI, so much the better: this kind of capital brings technology and skills from abroad packaged along with it, with less financial risk as well. In either case, the addition to investment ought to push incomes up, partly by raising the demand for labor and partly by making labor more productive. This why workers in FDI receiving countries should be in an even better position to profit from integration than workers in FDI sending countries. Also, with or without inflows of foreign capital, the same static and dynamic gains from trade should apply in developing countries as in rich ones. This gain from trade logic often arouses suspicion, because the benefits seem to come from nowhere. Surely one side or the other must lose. Not so. The benefits that a rich country gets though trade do not come at the expense of its poor country trading partners, or vice versa. Recall that according to the theory, trade is a positive sum game. In all these transactions, sides exporters and importers, borrowers and lenders, shareholders and workers can gain.

单选题The attitude of the author towards the research project is