单选题This line of inquiry did not begin until earlier this month—more than three months after the accident—because there were "too many emotions, too many egos," said retired Adm. Harold Gehman, chairman of the Columbia Accident Investigation Board. Testifying before the Senate Commerce Committee, Gehman said this part of his inquiry was in its earliest stages, starting just 10 days ago. But Gehman said he already has concluded it is "inconceivable" that NASA would have been unable or unwilling to attempt a rescue for astronauts in orbit if senior shuttle managers and administrators had known there was fatal damage to Columbia"s left wing. Gehman told reporters after the hearing that answers to these important questions could have enormous impact, since they could place in a different context NASA"s decisions against more aggressively checking possible wing damage in the days before Columbia"s fatal return. Investigators believe breakaway insulating foam damaged part of Columbia"s wing shortly after lift off, allowing superheated air to penetrate the wing during its fiery reentry on Feb. 1, melt it from inside. Among those decisions was the choice by NASA"s senior shuttle managers and administrators to reject offers of satellite images of possible damage to Columbia"s left wing before the accident. The subject dominated the early part of Wednesday"s hearing. Gehman complained managers and administrators "missed signals" when they rejected those offers for images, a pointedly harsh assessment of the space agency"s inaction during the 16-day shuttle mission. "We will attempt to pin this issue down in our report, but there were a number of bureaucratic and administrative missed signals here," Gehman told senators. "We"re not quite so happy with the process." The investigative board already had recommended that NASA push for better coordination between the space agency and military offices in charge of satellites and telescopes. The US National Imagery and Mapping Agency in March agreed to regularly capture detailed satellite images of space shuttles in orbit. Still, Gehman said it was unclear whether even images from America"s most sophisticated spy satellites might have detected on Columbia"s wing any damage, which Gehman said could have been as small as two inches square. The precise capabilities of such satellites proved to be a sensitive topic during the Senate hearing.

单选题Doctors strongly {{U}}recommend{{/U}} that fathers should be present at their baby's birth.

单选题The nurse's station is the only place where nurses in a hospital ward can be found.

单选题Early childhood education In a time of low academic achievement by children in the United States, many Americans are turning to Japan, a country of high academic achievement and economic success, for possible answers. However, the answers provided by Japanese preschools are not the ones Americans expected to find in most Japanese preschools, surprisingly little emphasis is put on academic instruction. In one investigation, 300 Japanese and 210 American preschool teachers, child development specialists, and parents were asked about various aspects of early childhood education. Only 2 percent of the Japanese respondents listed "to give children a good start academically" as one of their top three reasons for a society to have preschools. In contrast, over half the American respondents chose this as one of their top three choices. To prepare children for successful careers in first grade and beyond, Japanese schools do not teach reading, writing, and mathematics, but rather skills such as persistence, concentration, and the ability to function as a member of a group. The vast majority of young Japanese children are taught to read at home by their parents. In the recent comparison of Japanese and American preschool education, 91 percent of Japanese respondents chose providing children with a group experience as one of their top three reasons for a society to have preschools. Sixty-two percent of the more individually oriented (强调个性发展) Americans listed group experience as one of their top three choices. An emphasis on the importance of the group seen in Japanese early childhood education continues into elementary school education. Like in America, there is diversity in Japanese early childhood education. Some Japanese kindergartens have specific aims, such as early musical training or potential development. In large cities, some kindergartens are attached to universities that have elementary and secondary schools. Some Japanese parents believe that if their young children attend a university-based program, it will increase the children's chances of eventually being admitted to top-rated schools and universities. Several more progressive programs have introduced free play as a way out for the heavy intellectualizing in some Japanese kindergartens.

单选题Loud noises can be annoying .

单选题A Biological Clock Every living thing has what scientists call a biological clock that controls behavior. The biological clock tells 1 when to form flowers and when the flowers should open. It tells 2 when to leave the protective cocoons and fly away, and it tells animals and human beings when to eat, sleep and wake. Events outside the plant and animal 3 the actions of some biological clocks. Scientists recently found, for example, that a tiny animal changes the color of its fur 4 the number of hours of daylight. In the short 5 of winter, its fur becomes white. The fur becomes gray brown in color in the longer hours of daylight in summer. Inner signals control other biological clocks. German scientists found that some kind of internal clock seems to order birds to begin their long migration 6 twice each year. Birds 7 flying become restless when it is time for the trip, 8 they become calm again when the time of the flight has ended. Scientists say they are beginning to learn which 9 of the brain contain biological clocks. An American researcher, Martin Moorhead, said a small group of ceils near the front of the brain 10 to control the timing of some of our actions. These 11 tell a person when to 12 , when to sleep and when to seek food. Scientists say there probably are other biological clock cells that control other body activities. Dr. Moorhead is studying 13 our biological clocks affect the way we do our work. For example, most of us have great difficulty if we must often change to different work hours. 14 can take many days for a human body to accept the major change in work hours. Dr. Moorhead said industrial officials should have a better understanding of biological clocks and how they affect workers. He said 15 understanding could cut sickness and accidents at work and would help increase a factory"s production.

单选题Sleep Deficit(不足) Judging from recent surveys, most experts in sleep behavior agree that is virtually an epidemic of sleepiness in the nation. "I can't think of a single study that hasn't found Americans getting less sleep than they ought to. " says Dr. David. Even people who think they are sleeping enough would probably be better off with more rest. The beginning of our sleep-deficit crisis can be traced to the invention of the light bulb a century ago. From diary entries and other personal accounts from the 18th 19th centuries, sleep scientists have reached the conclusion that the average person used to sleep about 9.5 hours a night. "The best sleep habits once were forced on us, when we had nothing to do in the evening down on the farm, and it was dark. " By the 1950s and 1960s, that sleep schedule had been reduced dramatically, to between 7.5 and 8 hours, and most people had to wake to an alarm clock. "People cheat on their sleep, and they don't even realize they're doing it," says Dr. David. "They think they're okay because they can get by on 6.5 hours, when they really need 7.5,8 or even more to feel ideally vigorous. " "Perhaps the most merciless robber of sleep," researchers say, "is the complexity of the day. " Whenever pressures from work, family, friends and community mount, many people consider sleep the least expensive item on his program. "In our society, you're considered dynamic if you say you only need 5.5 hours' sleep. If you've got to get 8.5 hours, people think you lack drive and ambition. " To determine the consequences of sleep deficit, researchers have put subjects through a set of psychological and performance tests requiring them, for instance, to add columns of numbers or re call a page read to them only minutes earlier. "We've found that if you're in sleep deficit, perform ance suffers," says Dr. David. "Shot-term memory is weakened, as are abilities to make decision and to concentrate.

单选题The most pressing problem any economic system faces is how to use its scarce resources.A. puzzlingB. controversialC. terrifyingD. urgent

单选题I think she made a {{U}}blunder{{/U}} by announcing it ahead of time.

单选题 Look After Your Voice Often speakers at a meeting experience dry mouths and ask for a glass of water. You can solve the problem by activating the saliva in your mouth. First gently bite the edges of your tongue with your teeth. Or, press your entire tongue to the bottom of your mouth and hold it there until the saliva flow. Or you can imagine that you are slicing a big juicy lemon and sucking the juice. Before you begin your talk, be kind to your voice. Avoid milk or creamy drinks that coat your throat. Keep your throat wet by drinking a little sweetened warm tea or diluted fruit juice. If you sense that you are losing your voice, stop talking completely. Save your voice for your speech. You may feel foolish using paper to write notes, but the best thing you can do is to rest your voice. If you need to see a doctor, perhaps you can get some advice from a professional singer In the meantime, do not even talk in a low voice. What about drinking alcohol to wet your throat? I advice you not to touch alcohol before speaking. The problem with alcohol is that one drink gives you a little confidence. Two drinks gives you even more confidence. Finally you will feel all-powerful and you will feel you can do everything, but in fact your brain and your mouth do not work together properly. Save the alcohol until after you finish speaking. Perhaps you want to accept the advice, but you may wonder if you can change the habits of a lifetime. Of course you can. Goethe, who lived before indoor skating rinks or swimming pools, said, "we learn to skate in the summer and swim in the winter." Take this message to heart and give yourself time to develop your new habits. If you are willing to change, you will soon be able to say that you will never forget these techniques because they became a part of your body.

单选题Better Control of TB Seen If a Faster Cure Is Found The World Health Organization estimates that about one-third of all people are infected with bacteria that cause tuberculosis. Most times, the infection remains inactive. But each year about eight million people develop active cases of TB, usually in their (1) . Two million people die (2) it. The disease has (3) with the spread of AIDS and drug-resistant forms of tuberculosis. Current treatments take at least six months. Patients have to (4) a combination of several antibiotic drugs daily. But many people stop (5) they feel better. Doing that can (6) to an infection that resists treatment. Public health experts agree that a faster-acting cure for tuberculosis would be more effective. Now a study estimates just how (7) it might be. A professor of international health at Harvard University led the study. Joshua Salomon says a shorter treatment program would likely mean not just more patients (8) . It would also mean (9) infectious patients who can pass on their infection to others. The researchers developed a mathematical model to examine the effects of a two-month treatment plan. They (10) the model with current TB conditions in Southeast Asia. The scientists found that a two-month treatment could prevent about twenty percent of new cases. And it might (11) about twenty-five percent of TB deaths. The model shows that these (12) would take place between two thousand twelve and two thousand thirty. That is. if a faster cure is developed and in wide use by two thousand twelve. The World Health Organization (13) the DOTS program in nineteen ninety. DOTS is Directly Observed Treatment, Short-course. Health workers watch tuberculosis patients take their daily pills to make (14) they continue treatment. Earlier this year, an international partnership of organizations announced a plan to expand the DOTS program. The ten-year plan also aims to finance research (15) new TB drugs. The four most common drugs used now are more than forty years old. The Global Alliance for TB Drug Development says its long-term goal is a treatment that could work in as few as ten doses.

单选题You look smart in the new suit.

单选题The history of the exploration of Antarctica recounts many tales of perseverance and suffering.

单选题Stress Level Tied to Education Level People with less education suffer fewer stressful days, according to a report in the current issue of the Journal of Health and Social Behavior . However, the study also found that when less-educated people did suffer stress it was more severe and had a larger impact on their health. From this, researchers have concluded that the day-to-day factors that cause stress are not random. Where you are in society determines the kinds of problems that you have each day, and how well you will cope with them. The research team interviewed a national sample of 1,031 adults daily for eight days about their stress level and health. People without a high school diploma reported stress on 30 percent of the study days, people with a high school degree reported stress 38 percent of the time, and people with college degrees reported stress 44 percent of the time. "Less advantaged people are less healthy on a daily basis and are more likely to have downward turns in their health," lead researcher Dr. Joseph Grzywaez, of Wake Forest University Baptist Medical Center, said in a prepared statement. "The downward turns in health were connected with daily stressors and the effect of daily stressors on their health is much more devastating for the less advantaged." Grzywacz suggested follow-up research to determine why less-educated people report fewer days of stress when it is known their stress is more acute and chronic. "If something happens every day, maybe it"s not seen as a stressor." Grzywacz says. "Maybe it is just life."

单选题 阅读下面的短文，文中有15处空白，每处空白给出了4个选项，请根据短文的内容从 4个选项中选择1个最佳答案。 {{B}}A Special Clock{{/B}} Every living thing has what scientists call a biological clock that controls behavior. The biological clock______(51) plants when to form flowers and when the flowers should open. It tells insects when to______(52) the protective cocoon (防护卵袋) and fly away, and it tells animals and human beings when to eat, sleep and wake. Events outside the plant and animal______(53) the actions of some biological clocks. Scientists recently found, for example, that a tiny animal changes the color of its fur because of the______(54) of hours of daylight. In the short______(55) of winter, its fur becomes white. The fur becomes gray brown in______(56) in the longer hours of daylight in summer. Inner signals control other______(57) clocks. German scientists found that some kind of internal clock seems to order birds to begin their long migration ______(58) twice each year. Birds______(59) from flying become restless when it is time for the trip,______(60) they become calm again when the time Of the flight has ended. Scientists say they are beginning to learn which______(61) of the brain contain biological clocks. An American researcher, Martin Moorhead, said a small group of cells near the front of the brain______(62) to control the timing of some of our actions. These______(63) tell a person when to wake, when to______(64) and when to seek food. Scientists say there probably are other biological clock Cells that ______(65) other body activities.

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。{{B}}第一篇{{/B}} {{B}} Economic Costs of Noise{{/B}} The economic costs of noise to society are several. Airports are currently operating at less than capacity because of noise regulations which restrict their hours of operation. For in stance, at Washington's National Airport no jet traffic is allowed from 11 pm to 7 am. Other airports restrict the use of certain runways. One estimate is that noise restrictions reduce possible airport use by 20 percent. The profitable cargo trade is especially affected by night restrictions. In the case of airports, jet engines may be modified to reduce their noise level, or insulation(隔音) from air traffic noise may be provided by the purchase of land around airports or the insulation of buildings. One estimate is that ＄5.7 billion would be required to equip all existing jet engines with noise control devices. However, considering the current state of the art, even taking this step will not reduce noise levels at all points to acceptable values. Some combination of methods is probably necessary. If all aircraft were made quieter by existing methods, there would be a number of economic benefits. An increase in airport capacity would occur. Property values near airports might rise. Transportation costs to and from airports could be reduced since the airports now could be located closer to population centers. Much research still needs to be done on the economic aspects of noise reduction and noise effects. Although some of the effects of noise pollution are known, more must be discovered about its effects on health, productivity, property values and the quality of life. Furthermore, the cost of noise pollution control to the economy as a whole needs to be investigated. The public must be alerted to the dangers and economic costs of noise pollution so that people may make intelligent choices and exert appropriate pressures.

单选题It was very thoughtful of you to make all the necessary arrangements for us.

单选题Why are two shots thought to be necessary? People born after 1957 have not been exposed to a similar virus. The first dose "primes" (使准备好) the immune system to respond, but it's the second shot that triggers the production of antibodies. This is not unusual. A number of vaccines are given for the first time in multidose series. For example, the seasonal flu vaccine is given in two shots to children under 9 if they've never had the flu. What is the function of the first shot of the vaccine?A. To get the body ready for the second shot.B. To trigger the production of antibodies.C. To get the immune system ready to respond.D. To avoid unusual side effects of the vaccin

单选题Choosing Cosmetic Surgery Cosmetic surgery has increased dramatically in popularity over the past 10 years. With this increase in popularity, attitudes have changed as well. Fewer people are growing older gracefully, while more and more are accepting the cosmetic surgery alternative. Like nearly all fields, cosmetic surgery has undergone significant technological and conceptual (概念上的) changes in recent years. The conceptual changes have altered the approaches to facial aging, especially as they relate to the forehead, eyelids and lower face. Technological changes include the increasing use of the laser for facial cosmetic surgery, and minimally invasive techniques for face, breast and body contouring surgery. People undergo cosmetic surgery for many reasons. They may want to look younger for professional or personal reasons or change a feature they never liked. Whatever the reason, the data doesn' t lie. There were nearly 8.5 million cosmetic surgical and non - surgical procedures performed in 2001, an increase of 304% from 1997, according to the American Society for Aesthetic Plastic Surgery. The decision to undergo any type of cosmetic surgery is intensely personal. After all, this type of surgery is completely voluntary. Although cosmetic surgery will not change your life, it may give you greater self- confidence and add to your sense of well -being. However, do not make this decision lightly. It will not solve personal problems or make you look like someone else. When it comes to successful cosmetic surgery results, this is often dependent on the communication between you and your surgeon. Make sure you feel comfortable with your surgeon and that you feel you can communicate openly and honestly with him or her. It' s very important to be honest with yourself about why you want to correct a certain part of your body. Cosmetic surgery is a significant investment in time, effort, and emotion. It probably will not change your social life or your outlook on life. Take a minute to assess why you really want cosmetic surgery, and whether you have realistic expectations.

单选题Adaptation of Living Things Certain animals and plants develop characteristics that help them cope with their environment better than others of their kind. This natural biological process is called adaptation. Among the superior characteristics developed through adaptation are those that may help in getting food or shelter, in providing protection, and in producing and protecting the young. That results in the evolution of more and more organisms(生物体) that are better fitted to their environments. Each living thing is adapted to its way of life in a general way, but each is adapted especially to its own distinct class. A plant, for example, depends upon its roots to fix itself firmly and to absorb water and inorganic chemicals(无机物). It depends upon its green leaves for using the sun"s energy to make food from inorganic chemicals. These are general adaptations, common to most plants. In addition, there are special adaptations that only certain kinds of plants have. Many animals have adaptations that help them escape from their enemies. Some are hidden by their body color or shape, and many look like a leaf or a little branch. The coats of deer are colored to mix with the surroundings. Many animals have the ability to remain completely still when an enemy is near. Organisms have a great variety of ways of adapting. They may adapt in their structure, function, and genetics; in their development and production of the young; and in other respects. An organism may create its own environment, as do warm-blooded mammals(哺乳动物), which have the ability to adjust body heat exactly to maintain their ideal temperature despite changing weather. Usually adaptations are an advantage, but sometimes an organism is so well adapted to a particular environment that if conditions change, it finds it difficult or impossible to readapt to the new conditions.