单选题Many adults may think they are getting enough shut-eye, but in a major sleep study almost 80 percent of respondents admitted to not getting their prescribed amount of nightly rest. So, what exactly is the right amount of sleep? Research shows that adults need an average of seven to nine hours of sleep a night for optimal functionality. Read on to see just how much of an impact moderate sleep deprivation can have on your mind and body. By getting less than six hours of sleep a night, you could be putting yourself at risk of high blood pressure. When you sleep, your heart gets a break and is able to slow down for a significant period of time. But cutting back on sleep means your heart has to work overtime without its allotted break. In constantly doing so, your body must accommodate to its new conditions and elevate your overaI1 daily blood pressure. And the heart isn't the only organ that is overtaxed by a lack of sleeps. The less sleep you get, the less time the brain has to regulate stress hormones, and over time, sleep deprivation could permanently hinder the brain's ability to regulate these hormones, leading to elevated blood pressure. We all hang around in bed during our bouts of illness. But did you know that skipping out on the bed rest can increase your risk of getting sick? Prolonged sleep deprivation has long been associated with diminished immune functions, but researchers have also found a direct correlation between "modest" sleep deprivation—less than six hours—and reduced immune response. So try to toughen up your immune system by getting at least seven hours of sleep a night, and maintaining a healthy diet. You'll be glad you got that extra hour of sleep the next time that bug comes around and leaves everyone else bedridden with a fever for three days. During deep REM sleep, your muscles (except those in the eyes) are essentially immobilized in order to keep you from acting out on your dreams. Unfortunately, this effort your body makes to keep you safe while dreaming can sometimes backfire, resulting in sleep paralysis. Sleep paralysis occurs when the brain is aroused from its REM cycle, but the body remains in its immobilizing state. This can be quite a frightening sensation because, while your mind is slowly regaining consciousness, it has no control over your body, leaving some with a feeling of powerlessness, fear and panic. Most people experience this eerie phenomena at least once in their lives, but those who are sleep deprived are more likely to have panicked episodes of sleep paralysis that are usually accompanied by hallucinations, as well. For a second, imagine all of your memories are erased; every birthday, summer vacation, even what you did yesterday afternoon is completely lost, because you have no recollection of them. It's a chilling thought, but that is what a life without sleep would be like. Sleep is essential to the cognitive functions of the brain, and without it, our ability to consolidate memories, learn daily tasks, and make decisions is impaired by a large degree. Research has revealed that REM sleep, or dream-sleep, helps solidify the "fragile" memories the brain creates throughout the day to that they can be easily organized and stored in the mind's long-term cache.

单选题Later, as one went on to apply for more important lobs, one was advised to include in the letter ______.

单选题Most surveys find that people areU reluctant/U to place themselves at either the top or the bottom of the social ladder.

单选题For many people, overeating and overspending are as ______ to Christmas as candles and holly.(2002年厦门大学考博试题)

单选题He ______ interrupted me by asking many irrelevant questions. A. carelessly B. carefully C. continually D. consequently

单选题{{B}}Passage 4{{/B}} In most American cities, the rent for a one-bedroom apartment was $250 or more per month in recent years. In some smaller cities such as Louisville, Kentucky or Jacksonville, Florida the rent was less, but in larger cities it was more. For example, if you lived in Los Angeles, you had to pay $400 or more to rent a one-bedroom apartment, and the same apartment rented for $625 and up in Chicago. The most expensive rents in the U. S. were in New York City, where you had to pay at least $700 a month to rent a one-bedroom apartment in most parts of the city. Renters and city planners are worried about the high cost of renting apartments. Many cities now have rent control laws to keep the cost of renting low. These laws help low-income families who cannot pay high rents. Rent controls in the United States began in 1943 when the government imposed rent controls on all American cities to help workers and the families of soldiers during World War Ⅱ. After the war, only one city—New York—continued these World War Ⅱ controls. Recently, more and more cities have returned to rent controls. At the beginning of the 1980s, nearly one fifth of the people in the United States lived in cities with rent-control laws. Many cities have rent-control laws, but why are rents so high? Builders and landlords blame rent controls for the high rents. Rents are high because there are not enough apartments to rent, and they blame rent controls for the shortage of apartments. Builders want more money to build more apartment buildings, and landlords want more money to repair their old apartment buildings. But they cannot increase rents to get this money because of the rent-control laws. As a result, landlords are not repairing their old apartments, and builders are not building new apartment buildings to replace the old apartment buildings. Builders are building apartments for high-income families, not low income families, so low-income families must live in old apartments that are in disrepair. Builders and landlords claim that rent-control laws really hurt low income families. Many renters disagree with them. They say that rent control is not the problem. Even without rent controls, builders and landlords will continue to ignore low-income housing because they can make more money from high-income housing. The only answer, they claim, is more rent controls and government help for low-income housing.

单选题According to the passage, the rate of employment can be expected to rise when ______.

单选题Many theories concerning the causes of juvenile delinquency ( crimes committed by young people) focus either on the individual or on society as the major contributing influence. Theories (21) on the individual suggest that children engage in criminal behavior (22) they were not sufficiently penalized for previous misdeeds or that they have learned criminal behavior through (23) with others. Theories focusing on the role of society suggest that children commit crimes in (24) to their failure to rise above their socioeconomic status, (25) as a rejection of middle-class values. Most theories of juvenile delinquency have focused on children from disadvantaged families, (26) the fact that children from wealthy homes also commit crimes. The latter may commit crimes (27) lack of adequate parental control. All theories, however, are tentative and are (28) to criticism. Changes in the social structure may indirectly (29) juvenile crime rates. For example, changes in the economy that (30) to fewer job opportunities for youth and rising unemployment (31) make gainful employment increasingly difficult to obtain. The resulting discontent may in (32) lead more youths into criminal behavior. Families have also (33) changes these years. More families consist of one-parent households or two working parents; (34) , children are likely to have less supervision at home (35) was common in the traditional family structure.

单选题Walrus ivory, which the Eskimos used for weapons and carvings, is now very scarce due to the slaughter of the animals.

单选题______you need any further information, please do not hesitate to let me know.

单选题When most people think about changing their body shape, they usually focus on just losing weight. Books and magazines about dieting are among the most popular in the world. Dieting is an important part of staying fit and healthy, but losing weight by means of dieting takes time; losing weight too fast can cause great health problems. Dieting means change one"s eating habits to a healthier pattern, but many women mistake the concept of dieting and thinking that the less one eats, the better. As a result, they lose health as well as weight. Aerobic exercise is a moderate intensity workout that, over a certain period of time, will provide the body"s use of oxygen. Nowadays, aerobic exercise has become a very trendy workout among youths. Not only is performing aerobic exercise interesting, but it is also very beneficial for health. There are different types of aerobics like jogging, swimming, kickboxing, fitness walking, inline skating, bicycling, etc. Aerobics strengthens the heart and lungs. It is also especially popular with women. But neither of these two methods, dieting and aerobics, can help shape the body. To do this, you need to build muscle. So, if a firmer and shapelier body is your goal, 60 percent of your exercise routine should involve strengthening moves, and only 30 percent should be aerobic exercises. For a proper body-shaping routine, you should plan three strength-training sessions a week with weights. Use weights which are as heavy as possible while still allowing you to do 8 to 12 reps of each exercise. Do one to three exercises for each muscle groups—for example, chest and biceps, or back, shoulders and triceps. You should combine this with fast-paced aerobics activities, like swimming, cycling, walking, running, or in-line skating. Plan three to four workouts a week, 15 to 20 minutes each, increasing the pace each week. As you build muscle, you may find that you gain weight in spite of all of your calorie-burning exercise. Don"t worry. It"s probably muscle, which is denser that fat. And muscle is also a calorie-burning tissue. With more muscle, you can bum more calories, even when you are not exercising. When you are trying to build muscle, you need two to three servings of protein a day, but the main part of your diet should be carbohydrates. And in order to get the energy you need for a high-intensity workout, you should eat something, especially carbohydrates, an hour or so before your workout. While weight training will firm and shape your body, it has other benefits too. It improves bone and muscle strength and bums calories, leading to improved health and a higher quality of life.

单选题Looking ahead, the computer industry sees pure gold. Estimates for the number of personal computers in use by the end of the century run as high as 80 million. Then there are all the______industries; desks to hold computers, luggage to carry them, cleansers to polish them.

单选题To solve such a difficult problem is really ______ my grasp. A. beyond B. out of C. beneath D. away from

单选题Coincident with concerns about the accelerating loss of species and habitats has been a growing appreciation of the importance of biological diversity, the number of species in a particular ecosystem, to the health of the Earth and human beings. Much has been written about the diversity of terrestrial organisms, particularly the exceptionally rich life associated with tropical rain-forest habitats. Relatively little has been said, however, about diversity of life in the sea even though coral reef systems are comparable to rain forests in terms of richness of life. An alien exploring the Earth would probably give priority to the planet's dominant, most distinctive feature—the ocean. Humans have a bias toward land that sometimes gets in the way of truly examining global issues. Seen from far away, it is easy to realize that landmasses occupy one-third of the Earth's surface. Given that two-thirds of the Earth's surface is water and that marine life lives at all levels of the ocean, the total three- dimensional living space of the ocean is perhaps 100 times greater than that of land and contains more than 90 percent of all life on Earth even though the ocean has fewer distinct species. The fact that half of the known species are thought to inhabit the world's rain forests does not seem surprising, considering the huge numbers of insects that comprise the bulk of species. One scientist found many different species of ants in just one tree from a rain forest. While every species is different from every other species, their genetic makeup constrains them to be insects and to share similar characteristics with 750 000 species of insects. If basic, broad categories such as phyla and classes are given more emphasis than differentiating between species, then the greatest diversity of life is unquestionably the sea. Nearly every major type of plant and animal has some representation there. To appreciate fully the diversity of abundance of life in the sea, it helps to think small. Every spoonful of ocean water contains life on the order of 100 to 100 000 bacterial cells plus assorted microscopic plants and animals, including larva's or organisms ranging from sponges and corals to starfish and clams and much more.

单选题If I may be so______as to advise you, my opinion is that you should not reply to his letter. A. generous B. humble C. proud D. bold

单选题In spite of the ______ economic forecasts, manufacturing output has risen slightly. A. gloomy B. miserable C. shadowy D. obscure

单选题The Social Security Act did not include health insurance because the commission considered that its inclusion would jeopardize the passage of the act.

单选题If you've got a complaint, the best thing is to see the person concerned and ______with him. A. tell it B. have it out C. say it D. have it known

单选题 Passage 2 Believe it or not, optical illusion (错觉) can cut highway crashes. Japan is a case in point. It has reduced automobile crashes on some roads by nearly 75 percent using a simple optical illusion. Bent stripes, called chevrons (人字形)painted on the roads make drivers think that they are driving faster than they really are, and thus drivers slow down. Now the American Association Foundation for Traffic Safety in Washington D. C. is planning to repeat Japan's success. Starting next year, the foundation will paint chevrons and other patterns of stripes on selected roads around the country to test how well the patterns reduce highway crashes. Excessive speed plays a major role in as much as one fifth of all fatal traffic accidents, according to the foundation. To help reduce those accidents, the foundation will conduct its tests in areas where speed-related hazards are the greatest-curves, exit slopes, traffic circles, and bridges. Some studies suggest that straight, horizontal bars painted across roads can initially cut the average speed of drivers in half. However, traffic often returns to full speed within months as drivers become used to seeing the painted bar. Chevrons, scientists say, not only give drivers the impress ion that they are driving faster than they really are but also make a lane appear to be narrower. The result is a longer lasting reduction in highway speed and the number of traffic accidents.