单选题His laziness ______ his failure in the final exam,

单选题Which of the following can best express the main idea of the passage? ( )

单选题The molecules of carbon dioxide in the Earth's atmosphere affect the heat balance of the Earth by acting as a one-way screen. (1) these molecules allow radiation at visible wavelengths, where most of the energy of sunlight is concerned, to pass (2) , they absorb some of the longer-wave-length, infrared emissions radiated from the Earth's surface, radiation that would (3) be transmitted back into space. For the Earth to maintain a constant average temperature, such emissions from the planet must (4) incoming solar radiation. If there were no carbon dioxide in the atmosphere, heat would (5) from the Earth much more easily. Today, (6) , the potential problem is too much carbon dioxide. Could the increase in carbon dioxide (7) a global rise in average temperature, and could such a rise have serious (8) for human society? Mathematical models that allow us to calculate the rise in temperature as a function of the increase (9) ;that the (10) is probably yes. One mathematical model (11) that doubling the atmospheric carbon dioxide would raise the global mean surface temperature by 2.5℃. This model assumes that the atmosphere's relative humidity remains constant and the temperature decreases with altitude at a (12) of 6.5℃ per kilometer. The assumption of constant relative humidity is important, because water vapor in the atmosphere is another (13) absorber or radiation at infrared wavelengths. Because warm air can hold more (14) than cool air, the relative humidity will be constant (15) the amount of water vapor in the atmosphere increases (16) the temperature rises. (17) , more infrared radiation would be absorbed and reradiated (18) to the Earth's surface. The resultant warming at the surface could be expected to melt snow and ice, (19) the Earth's reflectivity. More solar radiation would be absorbed, (20) to a further increase in temperature.

单选题 To say that the child learns by imitation and that the way to teach is to set a good example oversimplifies. No child imitates every action he sees. Sometimes, the example the parent wants him to follow is ignored while he takes over contrary patterns from some other example. Therefore we must turn to a more subtle theory than 'Monkey see, monkey do'. Look at it from the child's point of view. Here he is in a new situation, lacking a ready response. He is seeking a response which will gain certain ends. If he laces a ready response for the situation, and cannot reason out what to do, he observes a model who seems able to get the right result. The child looks for an authority or expert who can show what to do. There is a second element at work in this situation. The child may be able to attain his immediate goal only to find that his method brings criticism from people who observe him. When shouting across the house achieves his immediate end of delivering a message, he is told emphatically that such a racket (叫嚷) is unpleasant, that he should walk into the next room and say his say quietly. Thus, the desire to solve any objective situation is overlaid with the desire to solve it properly. One of the early things the child learns is that he gets more affection and approval when his parents like his response. Then other adults award some actions and criticize others. If one is to maintain the support of others and his own self-respect, he must adopt responses his social group approves. In finding trial responses, the learner does not choose models at random. He imitates the person who seems a good person to be like, rather than a person whose social status he wished to avoid. If the pupil wants to be good violinist, he will observe and try to copy the techniques of capable players; while some other person may most influence his approach to books. Admiration of one quality often leads us to admire a person as a whole, and he becomes an identifying figure. We use some people as models over a wide range of situations, imitating much that they do. We learn that they are dependable and rewarding models because imitating them leads to success.

单选题She insisted that the seats _______  in advance.

单选题Most of the waiters are ______ in their work because the owner of the restaurant does not pay them on tinge.

单选题It was in the winter of 1951______a heavy fog moved into London.

单选题Hotel Receptionist: Front desk. Can I help you? Guest: This is Mr. Burton in 1205. ______?

单选题______ for you help, wed never have been able to get over the difficulties. A. Had it not been B. If it were not C. Had it not D. if we had not been

单选题Connie: Are you doing pottery? It looks like fun! Frank: ______ ? Connie: Boy, would I? Thanks.

单选题 It's possible to admire Oprah Winfrey and still wish Harvard hadn't awarded her an honorary doctor of law degree and the commencement (毕业典礼)speaker spot at yesterday's graduation. There's no question Oprah's achievements place her in the temple of American success stories. Talent, charm, and an exceptional work ethic have rarely hurled anyone as far as they have this former abused teenage mother from rural Mississippi who became one of the world's most successful entertainment icons and the first African-American female billionaire. Honorary degrees are often conferred on non-academic leaders in the arts, business, and politics. Harvard's list in recent years has included Kofi Annan, Bill Gates, Meryl Streep, and David Souter. But Oprah's particular brand of celebrity is not a good fit for the values of a university whose motto (座右铭), Veritas, means truth. Oprah's passionate advocacy extends, unfortunately, to a hearty embrace of fake science. Most notoriously, Oprah's validation of Jenny McCarthy's claim that vaccines cause autism (自闭症) has no doubt contributed to much harm through the foolish avoidance of vaccines. Famous people are entitled to a few failings like the rest of us, and the choice of commencement speakers often reflects a balance of institutional priorities and aspirations. Judging from our conversations with many students, Oprah was a widely popular choice. But this vote of confidence in Oprah sends a troubling message at precisely the time when American universities need to do more to advance the cause of reason. As former Dean of Harvard College, Harry Lewis, noted in a blog post about his objections, 'It seems very odd for Harvard to honor such a high profile popularizer of the irrational... at a time when political and religious nonsense so jeopardize the rule of reason in this allegedly enlightened democracy and around the world.' As America's oldest and most visible university, Harvard has a special opportunity to convey its respect for science not only through its research and teaching programs but also in its public affirmation of evidence-based inquiry. Unfortunately, many American universities seem awfully busy protecting their brand name and not nearly busy enough protecting the pursuit of knowledge. A recent article in The Harvard Crimson noted the shocking growth of Harvard's public relations arm in the last five years and it questioned whether a focus on risk management and avoiding controversy was really the best outward-looking face of this great institution. As American research universities begin to resemble profit centers and entertainment complexes, it's easy to lose sight of their primary mission: to produce and spread knowledge. This mission depends on traditions of rational discourse and vigorous defense of the scientific method. Oprah Winfrey's honorary doctorate was a step in the wrong direction.

单选题You may borrow this dictionary______you keep it clean.

单选题Students at these schools test far below the state average in reading, and their scores have improved only______

单选题 What is the most striking image to emerge from this autumn's Occupy protests? Was it the campus police officer in Davis, California, casually pepper-spraying a line of seated protesters? Or the white-shirted cop in New York, doing the same to a pair of unarmed, penned-in women? Perhaps it was a street in Oakland, deserted except for protesters and a line of black-helmeted riot police, the silence broken when one of the cops fires a rubber bullet at a protester filming him. Protesters have complained, as ever, about police infiltration, but as these videos were made clear, protesters and other citizens are keeping their eyes on police, too. More than two-thirds of Americans own digital cameras. Around one-third of adults own a smart phone. Most of these devices can record and easily transmit audio and video. Recording police has never been easier, and thanks to social-media and activist networks such as Copwatch, which monitors police activity and posts videos to the web, neither has publicizing these recordings. That does not always go over well. People peaceably filming police have been handcuffed, beaten, had their cameras seized, and been arrested for obstructing governmental administration, obstructing an investigation, interference, disturbing the peace, or for illegal wiretapping. In taking such action the police are on shaky legal ground. The right to photograph people, including police officers, in public places, is relatively clear. Adding audio, however, raises a new set of legal issues. Most states have single-party consent laws concerning audio recording, meaning that as long as one party consents to being recorded, the taping is legal. In most of the 12 states in which all parties must consent to be recorded, a violation occurs only if the subjects being recorded have a reasonable expectation of privacy. Arguing that police officers carrying out their duties in public have such a right is a challenge. The attorney-general in Maryland, an all-party-consent state, wrote in 2010 that few interactions with police could be considered private. And challenges are mounting in two of the states—Illinois and Massachusetts—without expectation-of-privacy clauses. In Massachusetts last August, a federal appeals court upheld a lower court's ruling that a citizen's right to film police in public is protected by the first and fourth amendments. During oral arguments, one of the judges hearing the challenges to the Illinois Eavesdropping Act worried that allowing recording might hinder the ability of the police to do their jobs. He gave the example of a policeman talking to a confidential informant. Police have also expressed concern about recording, and hence exposing, undercover officers. But of course police can still speak in private. Given the actions of some police officers when confronted with a camera, filming cops may not be prudent. But neither should it be illegal.

单选题It was ______ that asked Maury for help in oceanographic studies. ( )

单选题Scientists have been struggling to find out the reason behind blushing （脸红）。Why would humans evolve（进化） a 21__________ that puts us at a social disadvantage by 22__________ us to reveal that we have c

单选题What was suggested about the construction of a new city at sea?

单选题 Vitamin Truth and Lies A. Once upon a time, you believed in the tooth fairy. You counted on the stability of housing prices and depended on bankers to be, well, dependable. And you figured that taking vitamins was good for you. Oh, it's painful when another myth gets shattered. Recent research suggests that a daily multi is a waste of money for most people—and there's growing evidence that some other old standbys (备用物品) may even hurt your health. Here's what you need to know. Myth: a multivitamin can make up for a bad diet B. An insurance policy in a pill? If only it were so. Last year, researchers published new findings from the Women's Health Initiative, a long-term study of more than 160000 midlife women. The data showed that multivitamin-takers are no healthier than those who don't pop the pills, at least when it comes to the big diseases—cancer, heart disease, stroke. 'Even women with poor diets weren't helped by taking a multivitamin,' says study author Marian Neuhouser, Ph. D., in the cancer prevention program at the Fred Hutchinson Cancer Research Center, in Seattle. C. Vitamin supplements came into fashion in the early 1900s, when it was difficult or impossible for most people to get a wide variety of fresh fruits and vegetables year-round. Back then, vitamin-deficiency diseases weren't unheard of: the bowed legs and deformed ribs of rickets (caused by a severe shortage of vitamin D) or the skin problems and mental confusion of pellagra (caused by a lack of the B vitamin niacin). But these days, you're extremely unlikely to be seriously deficient if you eat an average American diet, if only because many packaged foods are vitamin-enriched. Sure, most of us could do with a couple more daily servings of produce, but a multi doesn't do a good job at substituting for those. 'Multivitamins maybe have two dozen ingredients—but plants have hundreds of other useful compounds,' Neuhouser says. 'If you just take a multivitamin, you're missing lots of compounds that may be providing benefits.' D. That said, there is one group that probably ought to keep taking a multivitamin: women of reproductive age. The supplement is insurance in case of pregnancy. A woman who gets adequate amounts of the B vitamin foliate is much less likely to have a baby with a birth defect affecting the spinal cord (脊髓). Since the spinal cord starts to develop extremely early—before a woman may know she's pregnant—the safest course is for her to take 400 micrograms of folic acid (叶酸) (the synthetic form of foliate) daily. And a multi is an easy way to get it. Myth: vitamin C is a cold fighter E. In the 1970s, Nobel laureate Linus Pauling popularized the idea that vitamin C could prevent colds. Today, drugstores are full of vitamin C-based remedies. Studies say: Buyer, beware. In 2007, researchers analyzed a raft of studies going back several decades and involving more than 11000 subjects to arrive at a disappointing conclusion: Vitamin C didn't ward off colds, except among marathoners, skiers, and soldiers on subarctic exercises. F. Of course, prevention isn't the only game in town. Can the vitamin cut the length of colds? Yes and no. Taking the vitamin daily does seem to reduce the time you'll spend sniffling—but not enough to notice. Adults typically have cold symptoms for 12 days a year; a daily pill could cut that to 11 days. Kids might go from 28 days of runny noses to 24 per year. The researchers conclude that minor reductions like these don't justify the expense and bother of year-round pill-popping (taking C only after symptoms crop up doesn't help). Myth: vitamin pills can prevent heart disease G. Talk about exciting ideas—the notion that vitamin supplements might help lower the toll of some of our most damaging chronic diseases turned a sleepy area of research into a sizzling- hot one. These high hopes came in part from the observation that vitamin-takers were less likely to develop heart disease. Even at the time, researchers knew the finding might just reflect what's called the healthy user effect—means that vitamin devotees are more likely to exercise, eat right, and resist the temptations of tobacco and other bad habits. But it was also possible that antioxidant vitamins like C, E, and beta-carotene (β-胡萝卜素) could prevent heart disease by reducing the buildup of artery-clogging plaque (牙斑). B vitamins were promising, too, because foliate, B6, and B12 help break down the amino acid homocysteine (同型半胱氨酸)—and high levels of homocysteine have been linked to heart disease. Unfortunately, none of those hopes have panned out H. An analysis of seven vitamin E trials concluded that it didn't cut the risk of stroke or of death from heart disease. The study also scrutinized eight beta-carotene studies and determined that, rather than prevent heart disease, those supplements produced a slight increase in the risk of death. Other big studies have shown vitamin C failing to deliver. As for B vitamins, research shows that yes, these do cut homocysteine levels... but no, that doesn't make a dent in heart danger. I. Don't take these pills, the American Heart Association says. Instead, the AHA offers some familiar advice: Eat a varied diet rich in fruits, vegetables, and whole grains. Myth: taking vitamins can protect against cancer J. Researchers know that unstable molecules called free radicals (自由基) can damage your cells' DNA, upping the risk of cancer. They also know that antioxidants can stabilize free radicals, theoretically making them much less dangerous. So why not take some extra antioxidants to protect yourself against cancer? Because research so far has shown no good comes from popping such pills. K. A number of studies have tried and failed to find a benefit, like a recent one that randomly assigned 5 442 women to take either a placebo or a B-vitamin combo (混合物). Over the course of more than seven years, all the women experienced similar rates of cancers and cancer deaths. In Neuhouser's enormous multivitamin study, that pill didn't offer any protection against cancer either. Nor did C, E, or beta-carotene in research done at Harvard Medical School. Truth: a pill that's worth taking L. As studies have eroded the hopes placed in most vitamin supplements, one pill is looking better and better. Research suggests that vitamin D protects against a long list of ills. Men with adequate levels of D have about half the risk of heart attack as men who are deficient. And getting enough D appears to lower the risk of at least half a dozen cancers; indeed, epidemiologist Cedric Garland, MD, at the University of California, San Diego, believes that if Americans got sufficient amounts of vitamin D, 50000 cases of colorectal (结肠直肠的) cancer could be prevented each year. M. But many—perhaps most—Americans fall short, according to research by epidemiologist Adit Ginde, MD, at the University of Colorado, Denver. Vitamin D is the sunshine vitamin. You make it when sunlight hits your skin. Yet thanks to sunscreen and workaholic (or TV-aholic) habits, most people don't make enough. N. How much do you need? The Institute of Medicine is reassessing that right now; most experts expect a big boost from the current levels (200 to 600 IU daily). It's safe to take 1000 IU per day, says Ginde. 'We think most people need at least that much.' O. So here's the truth about vitamins. Eat right, and supplement with vitamin D. That's a no-brainer coupled with a great bet—and that's no lie.

单选题 Which of the following is a stative verb (静态动词)?

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