单选题It is postulated that a cure for the disease will have been found by the year 2020. A. challenged B. assumed C. deducted D. decreed

单选题Which of the following statements is true about an average car according to the passage?

单选题He was kept in appalling conditions in prison.

单选题With immense relief I stopped running. A. no B. little C. scarce D. enormous

单选题It can be learnt from the last paragraph that _____.

单选题Nuclear Power and Its Danger Nuclear power"s danger to health, safety, and even life itself can be summed up in one word: radiation. Nuclear radiation has a certain mystery about it, partly because it cannot be detected by human senses. It can"t be seen or heard, or touched, or tasted, even though it may be all around us. There are other things like that. For example, radio waves are all around us but we can"t detect them, sense them, without a radio receiver. Similarly, we can"t sense radioactivity without a radiation detector. But unlike common radio waves, nuclear radiation is not harmless to human beings and other living things. At very high levels, radiation can kill an animal or human being outfight by killing masses of cells in vital organs. But even the lowest level of radiation can do serious damage. There is no level of radiation that is completely safe. If the radiation does not hit anything important, the damage may not be significant . This is the case when only a few cells are hit, and if they are killed outright. Your body will replace the dead cells with healthy ones. But if the few cells are only damaged, and if they reproduce themselves, you may be in trouble. They reproduce themselves in a deformed way. They can grow into cancer. Sometimes this does not show up for many years. This is another reason for some of the mystery about nuclear radiation. Serious damage can be done without the victim being aware at the time that damage has occurred. A person can be irradiated and feel fine, then die of cancer five, ten, or twenty years later as a result. Or a child can be born weak or liable to serious illness as a result of radiation absorbed by its grandparents. Radiation can hurt us. We must know the truth.

单选题Lowering the Risk of Heart Disease Like millions of other Americans, I come from a family with a history of the heart disease. My father had his first three heart attacks when he was only thirty-one. I was three years old at that time. I grew up with heart disease. It was there, but I didn"t take it seriously. When I was thirty-one, my blood cholesterol (胆固醇) level was measured for the first time. It was 311 mg/dl, the doctor told me-an extremely high level that put me at a very high risk of heart disease, especially with my family history. He sent me to the National Institutes of Health (NIH) to be screened for participation in a clinical trial. The trial was designed to test the effect of lowering blood cholesterol on the risk of heart disease. At NIH, physicians explained the degree of risk associated with my blood cholesterol level and the nature of the experiment. This test involves putting a tube through a leg artery (动脉) up to the heart. The death rate for the test was only 1 in 100, I was assured. Learning about the risks of the experiment as well as the risk associated with my raised blood cholesterol level scared the life out of me. Although I was excluded from participating in the study, the experience may well have saved my life. For the first time, I began to realize the seriousness of high blood cholesterol. It was a heart attack just waiting to happen. But equally important, I got a taste of what it is like to be a patient, to have tests done on me and to think of myself as sick. This was hard to take. This experience taught me two lifesaving lessons. First, although I felt fit and strong, I was actually at high risk for heart disease because of my high blood cholesterol level. And with my family history, it could not be ignored. Second, I could lower my blood cholesterol level simply by changing what I ate.

单选题Mother Nature Shows Her Strength Tornadoes (龙卷风) and heavy thunderstorms moved across the Great Lakes and into Trumhull County on Saturday evening. The storms were dramatic and dangerous. George Snyder was driving the fire truck down Route 88 when he first noticed that a funnel (漏斗状的) cloud was behind him. "I stopped the truck and watched the funnel cloud. It was about 100 feet off the ground and I saw it go up and down for a while. It was moving toward Bradley Road and then suddenly it disappeared, "Snyder said. Snyder only saw one of the funnel clouds that passed through northeastern Ohio on Saturday. In Trumbull County, a tornado turned trees onto their sides. Some trees fell onto houses and cars. Other trees fell into telephone and electrical wires as they went down. Amanda Symcheck was having a party when the storm began. "I knew something was wrong," she said. "I saw the sky go green and pink (粉红色). Then it sounded like a train rushing toward the house. I started crying and told everyone to go to the basement for protection. " The tornado caused a lot of damage to cars and houses in the area. It will take a long time and much money to repair everything. There was also serious water damage from the thunderstorms. The heavy rains and high wind caused the power to go out in many homes. The storms caused serious flooding in areas near the river. More than four inches of rain fell in parts of Trumbull County. The river was so high that the water ran into streets and houses. Many streets had to be closed to cars and trucks because of the high water. This made it difficult for fire trucks, police cars, and other rescue vehicles to help people who were in trouble. Many people who live near the river had to leave their homes for their own safety. Some people reported five feet of water in their homes. Local and state officials opened emergency shelters for the people who were evacuated (撤走). The Red Cross served meals to them. "This was a really intense storm, "said Snyder, "People were afraid. Mother Nature can be fierce. We were lucky this time. No one was killed. /

单选题Medical Journals Medical journals are publications that report medical information to physicians and other health professionals. In the past, these journals were available only in print. With the development of electronic publishing, many medical journals now have Web sites on the Internet, and some journals publish only online. A few medical journals, like the Journal of the American Medical Association, are considered general medical journals because they cover many fields of medicine. Most medical journals are specialty journals that focus on a particular area of medicine. Medical journals publish many types of articles. Research articles report the results of research studies on a range of topics varying from the basic mechanisms of diseases to clinical trials that compare outcomes of different treatments. Review articles summarize and analyze the information available on a specific topic based on a careful search of the medical literature. Because the results of individual research studies can be affected by many factors, combining results from different studies on the same topic can be helpful in reaching conclusions about the scientific evidence for preventing, diagnosing or treating a particular disease. Case conferences and case reports may be published in medical journals to educate physicians about particular illnesses and how to treat at them. Editorials in medical journals are short essays that express the views of the authors, often regarding a research or review article published in the same issue. Editorials provide perspective on how the current article fits with other information on the same topic. Letters to the editor provide a way for readers of the medical journal to express comments, questions or criticisms about articles published in that journal.

单选题he passage mentions all of the following facts EXCEPT

单选题His words activated my spirit.

单选题Who Want to Live Forever? If your doctor could give you a drug that would let you live a healthy life for twice as long, would you take it? The good news is that we may be drawing near to that date. Scientists have already extended the lives of flies, worms and mice in laboratories. Many now think that using genetic treatments we will soon be able to extend human life to at least 140 years. This seems a great idea. Think of how much more time we could spend chasing our dreams, spending time with our loved ones, watching our families grow and have families of their own. "Longer life would give us a chance to recover from our mistakes and promote long term thinking," says Dr. Gregory Stock of the University of California School of Public Health. "It would also raise productivity by adding to the year we can work." Longer lives don"t just affect the people who live them. They also affect society as a whole. "We have war, poverty, all sorts of issues around, and I don"t think any of them would be at all helped by having people live longer," says US bioethicist Daniel Callahan. "The question is "What will we get as a society?" I suspect it won"t be a better society." It would certainly be a very different society. People are already finding it more difficult to stay married. Divorce rates are rising. What would happen to marriage in a society where people lived for 140 years? And what would happen to family life if 9 or 10 generations of the same family were all alive at the same time? Research into ageing may enable women to remain fertile for longer. And that raises the prospect of having 100-year-old parents, or brothers and sisters born 50 years apart. We think of an elder sibling as someone who can protect us and offer help and advice. That would be hard to do if that sibling came from a completely different generation. Working life would also be affected, especially if the retirement age was lifted. More people would stay in work for longer. That would give us the benefits of age-skill, wisdom and good judgment. On the other hand, more people working for longer would create greater competition for jobs. It would make it more difficult for younger people to find a job. Top posts would be dominated by the same few individuals, making career progress more difficult. And how easily would a 25-year-old employee be able to communicate with a 125-year-old boss? Young people would be a smaller part of a society in which people lived to 140. It may be that such a society would place less importance on guiding and educating young people, and more on making life comfortable for the old. And society would feel very different if more of its members were older. There would be more wisdom, but less energy. Young people like to move about. Old people like to sit still. Young people tend to act without thinking. Old people tend to think without acting. Young people are curious and like to experience different things. Old people are less enthusiastic about change. In fact, they are less enthusiastic about everything. The effect of anti-ageing technology is deeper than we might think. But as the science advances, we need to think about these changes now. "If this could ever happen, then we"d better ask what kind of society we want to get," says Daniel Callahan. "We had better not go anywhere near it until we have figure those problems out."

单选题His knowledge of French is Ufair/U.

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Although originally a German innovation, kindergarten got its real start in the United States as a movement to provide an improved learning environment for children.

单选题We are worried about this fluid situation full with uncertainty.

单选题The drinking water has become contaminated with lead.

单选题If you consider this problem in terms of others" interest, you may change your view.

单选题Mary gets up at six o"clock every morning.

单选题When we listen to music, we are easily {{U}}put in mind{{/U}} of events in the past. A. remembered B. reflected C. memorized D. reminded