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.

单选题When the millionaire died, his son was left a lot of wealth.A. luckB. resourceC. propertyD. formation

单选题Please put up your hands if you have any questions. A. raise B. reach C. wave D. fold

单选题When she was invited to the party, she Ureadily/U accepted.

单选题 A Memory Drug? It's difficult to imagine many things that people would welcome more than a memory-enhancing drug. A memory enhancer could help eliminate forgetting associated with aging and disease. Furthermore, such a drug could help people remember past experiences more {{U}} {{U}} 1 {{/U}} {{/U}}and help us acquire new information more easily for school and at work. As scientists learn more about {{U}} {{U}} 2 {{/U}} {{/U}},we are closing in on this tantalizing goal. Some of the most exciting evidence comes from research that has built on earlier findings linking LTP and memory to identify a gene that improves memory in mice. The gene makes a protein that assists the NMDA receptor, which plays an important {{U}} {{U}} 3 {{/U}} {{/U}}in long-term memory by helping to initiate LTP. Mice bred to have extra copies of this gene showed more activity in their NMDA receptors, more LTP, and {{U}} {{U}} 4 {{/U}} {{/U}}performance on several different memory tasks—learning a spatial layout, recognizing familiar objects, and recalling a fear-inducing shock. If these basic insights about genes, LTP, and the synaptic basis of memory can be {{U}} {{U}} 5 {{/U}} {{/U}}to people-and that remains to be seen—they could pave the way for memory-enhancing treatments. {{U}} {{U}} 6 {{/U}} {{/U}}steroids for bulking up the muscles, these drugs would bulk up memory. As exciting as this may {{U}} {{U}} 7 {{/U}} {{/U}}, it also raises troubling issues. Consider the potential educational implications of memory-enhancing drugs. If memory enhancers were available, children {{U}} {{U}} 8 {{/U}} {{/U}}used them might be able to acquire and retain extraordinary amounts of information, allowing them to progress far more rapidly in {{U}} {{U}} 9 {{/U}} {{/U}}than they could otherwise. How well could the brain handle such an onslaught of information? What happens to children who don't have access to the latest memory enhancers? Are they left behind in school—and as a result handicapped later in life? What are the potential implications of memory-enhancing drugs for the workplace? Imagine that you are {{U}} {{U}} 10 {{/U}} {{/U}}for a job that requires a good memory, such as a manager at a technology company or a sales position that requires remembering customers' names as well as the attributes of different products and services. Would you take a memory-enhancing drug to increase your chances of landing the position? {{U}} {{U}} 11 {{/U}} {{/U}}people who felt uncomfortable taking such a drug find themselves cut out of lucrative career opportunities? Memory drugs might also help take the sting out of disturbing memories that we wish we could forget {{U}} {{U}} 12 {{/U}} {{/U}}can't. The 2004 hit movie Eternal Sunshine of the Spotless Mind told the story of a young man seeking just such freedom {{U}} {{U}} 13 {{/U}} {{/U}}the painful memories of a romantic breakup. As you will see in the section on persistence later in the chapter, emotionally arousing events often create intrusive memories, and researchers have already muted emotional memories with drugs that block the action of key hormones. Should emergency workers who must confront horrifying accident scenes that can {{U}} {{U}} 14 {{/U}} {{/U}}them with persisting memories be provided with such drugs? Should such drugs be given to rape victims who can't forget the trauma? Memory drugs might provide some relief to such individuals. But could they also interfere with an individual's ability to assimilate and come to terms with a difficult experience? We may find ourselves {{U}} {{U}} 15 {{/U}} {{/U}}these kinds of questions in the not-to-distant future.

单选题The Marketing Mix Marketing is a total system of business activites designed to plan, price, promote, and distribute want-satisfying products to target markets to achieve organizational objectives. This definition implies that the entire system of business activitiis should be customer-oriented, and a marketing program should start with an idea about a new product and should not end until the customer's wants are completely satisfied, which may be sometime after the sale is made. The combination of the four primary elements that comprise a company's marketing program is termed the marketing mix. The design, implementation, and evaluation of the marketing mix constitute the bulk of a firm's marketing effort. The four elements of the marketing mix are. ·Product—Managing the product ingredient includes planning and developing the right goods and/or services to be marketed by the company. Strategic decisions are also needed for changing existing products, adding new ones, and taking other actions that affect the assortment(分类) of products carried. Strategic decisions are also needed regarding branding, packaging, and various other product features. ·Price—Management must determine the right base price for its products. It must then decide on strategies concerning discounts, freight (货运) payments, and many other price-related factors. ·Distribution—Even though marketing intermediaries(中介)— primarily wholesalers and retailers are largely a noncontrollable environmental factor, an executive has considerable latitude when working with them. Management's responsibility is to select and manage the trade channels through which the products will reach the right market at the right time and develop a distribution system for physically handling and transporting the products through these channels. ·Promotion—Management needs to inform and persuade the market regarding a company's products. Advertising, personal selling, sales promotion and publicity are the major promotional activities. The four ingredients in the marketing mix are interrelated; decisions in one area usually affect actions in the others. Each of the four also contains countless variables. A company may market one item or several—related or unrelated. The item may be distributed through wholesalers or directly to retailers, and so on. Ultimately (最后) ,from the multitude of variables, management must select the combination that will best adapt to the environment, satisfy target markets, and still meet marketing and organizational goals.