单选题The only solution to rubbish problem for a nation which now spends more on wrapping food than it pays farmers to produce it, is recovering ______ the packaging materials for commercial as well as for conservation reasons. A. on sale B. on the spot C. on a large scale D. on all sides

单选题Working memory, or short-term memory, involves the ability to hold and use information in the immediate future. 21 is only held in working memory for about 20 seconds. The challenge that students 22 is to move information from their working memories into their long-term memories. If they don"t do this in about the first few minutes after receiving the information, that information can be lost. To keep this newly learned material from 23 away, it needs to enter the network of the brain"s wiring. After repeated practice, working memories are set down as permanent neuronal (神经的) circuits 24 to be activated (激活) when the information is needed. When a memory has been recalled 25 its neuronal circuits are more highly developed because of their repeated activation. 26 exercising a muscle, these circuits then become more efficient and easier to access and activate. Practice results 27 repeated stimulation of the memory circuit. Like hikers along a path 28 eventually leave a depression in the road, repeated practice stimulates cells in the memory circuit such that the circuit is reinforced and becomes 29 . This means it can be quickly turned from off to on, and switched 30 through a variety of cues coming in from the senses.

单选题Have you ever been startled by a loud noise or by someone appearing suddenly behind you on dark night or by a snake in the grass? Do you remember the sudden, tight feeling in your chest, the way your heart started go pound, the way you seemed to breathe more rapidly? Such reactions occurred because you were frightened. Your brain sent a signal to the special gland (腺) in your body caned the adrenal (肾上的) gland. Other parts of your body were involved, too, but the adrenal gland has a very special function. The adrenal gland is located on top of your kidney. Since you have two kidneys. You also have two adrenal glands. Each adrenal gland is divided into two parts: a cortex (外皮) and a medulla (髓质). The cortex forms the outer shell; the medulla forms the central core. Both the cortex and the medulla secrete (分泌) hormones, but they have different functions. The cortex produces more than forty different chemical compounds and hormones. All these things are essential to sustain life. The medulla secretes adrenalin (also called epinephrine, the hormone that prepares the body for emergencies.) When you are suddenly faced with a dangerous or stressful situation, part of your brain instantly sends a signal to the adrenal gland, and all sorts of things begin to your body. The medulla releases an extra amount of adrenalin into the bloodstream. The adrenalin is carried rapidly throughout the body, stimulating other glands and systems.

单选题We all know that it is possible for ordinary people to make their homes on the equator (赤道), although often they may feel uncomfortably hot there. Millions do it. But as for the North Pole (北极)--we know that it is not only a dangerously cold place, but that people like you and me would find it quite impossible to live there. At the present time only the scientists and explorers can do so, and they use special equipment. Men had been traveling across and around the equator on wheels, on their feet or in ships for thousands of years; but only a few men, with great difficulty and in very recent time, have ever crossed the ice to the North Pole. So it may surprise you to learn that, when traveling by air, it is really safer to fly over the North Pole than over the equator. Of course, this is not true about landings in the polar region (which passenger aeroplanes do not make), but the weather, if we are flying at a height of 5000 meters above the Pole, is a delight. At 4 000 meters and More above the earth you can always be sure that you will not see a cloud in the sky as far as the eye can reach. In the tropics (热带), on the other hand, you are not certain to keep clear of bad weather even at such heights as 18 000 or 20 000 meters. Aeroplanes can't climb as high or as quickly in cold air as in warm air. Nor can clouds. In practice, this is an advantage to the aeroplane, which is already at a good height when it reaches the polar region and so does not need to climb, while at the same time cold air keeps the clouds down low.

单选题Generally speaking, a British is widely regarded as a quiet, shy and conservative person who is (1) only among those with whom he is acquainted. When a stranger is at present, he often seems nervous, even (2) . You have to take a commuter train any morning or evening to (3) the truth of this. Serious-looking businessmen and women sit reading their newspapers or dozing in a corner; hardly anybody talks, since to do so would be considered quite (4) . (5) , there is an unwritten but clearly understood code of behavior which, once broken, makes the offender immediately the object of (6) . It has been known as a fact that a British has a (7) for the discussion of their weather and that, if given a chance, he will talk about it (8) . Some people argue that it is because the British weather seldom (9) forecast and hence becomes a source of interest and (10) to everyone. This may be so. (11) a British cannot have much (12) in the weathermen, who, after promising fine, sunny weather for the following day, are often proved wrong (13) a cloud over the Atlantic brings rainy weather to all districts! The man in the street seems to be as accurate — or as inaccurate — as the weathermen in his (14) . Foreigners may be surprised at the number of references (15) weather that the British (16) to each other in the course of a single day. Very often conversational greetings are (17) by comments on the weather. “Nice day, isn’t it?” “Beautiful!” may well be heard instead of “Good morning, how are you?” Although the foreigner may consider this exaggerated and comic, it is (18) .pointing out that it could be used to his advantage. If he wants to start a conversation with a British but is at a loss to know (19) to begin, he could do well to mention the state of the weather. It is a safe subject which will (20) an answer from even the most reserved of the British.

单选题It is not clear whether the increase in reports is {{U}}stemmed{{/U}} from greater human activity or is simply the result of more surveys.

单选题The most central function of the Congress is to______in the U. S.

单选题There is much discussion today about whether economic growth is desirable at an earlier period; our desire for material wealth may have been justified. Now, however, this desire for more than we need is causing serious problems. Even though we have good intentions, we may be producing too much, too fast. Those who criticize economic growth argue that we must slow down. They believe that society is approaching certain limits on growth. There include the fixed supply of natural resources, the possible negative effects of industry on the natural environment, and the continuing increase in the world"s population. As society reaches these limits, economic growth can no longer continue, and the quality of life will decrease. People who want more economic growth, on the other hand, argue that even at the present growth rate there are still many poor people in the world. These proponents of economic growth believe that only more growth can create the capital needed to improve the quality of life in the world. Furthermore, they argue that only continued growth can provide the financial resources required to protect our natural surroundings from industrialization. This debate over the desirability of continued economic growth is of vital importance to business and industry. If those who argue against economic growth are correct, the problems they mention cannot be ignored. To find a solution, economists and the business community must pay attention to these problems and continue discussing them with one another. We may infer from the context that "Proponents" (Para. 3) most probably means ______.

单选题{{B}}26-30{{/B}} While still in its early stages, welfare reform has already been judged a great success in many states, at least in getting people off welfare. It's estimated that more than 2 million people have left the rolls since 1994. In the past four years, welfare rolls in Athens County have been cut in half. But 70 percent of the people who left in the past two years took jobs that paid less than $6 an hour. The result: The Athens County poverty rate still remains at more than 30 percent—twice the national average. For advocates (代言人) for the poor, that's an indication much more needs to be done. "More people are getting jobs, but it's not making their lives any better," says Kathy Lairn, a policy analyst at the Center on Budget and Policy Priorities in Washington. A center analysis of U.S. Census data nationwide found that between 1995 and 1996, a greater percentage of single, female-headed households were earning money on their own, but that average income for these households actually went down. But for many, the fact that poor people are able to support themselves almost as well without government aid as they did with it is in itself a huge victory. "Welfare was a poison. It was a toxin (毒素) that was poisoning the family," says Robert Rector, a welfare-reform policy analyst. "The reform is changing the moral climate in low-income communities. It's beginning to rebuild the work ethic (道德观), which is much more important." Mr. Rector and others argued that once "the habit of dependency is cracked", then the country can make other policy changes aimed at improving living standards.

单选题The picture was bought at a very low price, but it has turned out to be a(n) ______ painting. A) invaluable B) invariable C) worthless D) valueless

单选题We could not even look at the sun, for otherwise we______.

单选题—______ I help you with some shoes，madam? —Yes．I would like to try on those brown ones．A．WillB．ShouldC．MayD．Must

单选题Sport is heading for an indissoluble marriage with television and the passive spectator will enjoy a private paradise. All of this will be in the future of sport. The spectator (the television audience) will be the priority and professional clubs will have to readjust their structures to adapt to the new reality: sport as a business. The new technologies will mean that spectators will no longer have to wait for broadcasts by the conventional channels. They will be the ones who decide what to see. And they will have to pay for it. In the United States the system of the future has already started: pay-as-you-view. Everything will be offered by television and the spectator will only have to choose. The review Sports Illustrated recently published a full profile of the life of the supporter at home in the middle of the next century. It explained that the consumers would be able to select their view of the match on a gigantic, flat screen occupying the whole of one wall, with images of a clarity which cannot be foreseen at present; they could watch from the trainer"s bench, from the stands just behind the batter in a game of baseball or from the helmet of the star player in an American football game. And at their disposal will be the same options the producer of the recorded program has: to select replays, to choose which camera to use and to decide on the sound-whether to hear the public, the players, the trainer and so on. Many sports executives, largely too old and too conservative to feel at home with the new technologies, will believe that sport must control the expansion of television coverage in order to survive and ensure that spectators attend matches. They do not even accept the evidence which contradicts their view: while there is more basketball than ever on television, for example, it is also certain that basketball is more popular than ever. It is also the argument of these sports executives that television is harming the modest team. This is true, but the future of those teams is also modest. They have reached their ceiling. It is the law of the market. The great events continually attract larger audience. The world is being constructed on new technologies so that people can make the utmost use of their time and, in their home, have access to the greatest possible range of recreational activities. Sport will have to adapt itself to the new world. The most visionary executives go further. Their philosophy is: rather than see television take over sport, why not have sports take over television?

单选题In March Israel launched a major ______ of Lebanon, seizing about 10 percent of the land.

单选题The author thinks of the explanation given by the army as______

单选题The hijackers should have been arrested ______ instead of being allowed to leave.

单选题Your sister used to visit you quite often, ______? A. isn't she B. use not she C. wasn't she D. didn't she

单选题Every time a person eats something he makes a nutritional decision. He accepts or rejects the food available to him at home for meals or snacks. Or he selects food for himself at many places in the community, such as supermarkets, drive-ins, restaurants, and food counters in drug stores. (83) These selections make a difference in how an individual looks, how he feels, and how well he can work and play. When a good assortment of food in appropriate amounts is selected and eaten, the consequences are more likely to be a desirable level of health and enough energy to allow one to be as active as he needs and wants to be. When choices are less than desirable, the consequences are likely to be poor health or limited energy or both. Studies of diets of individuals in the United States show that food selection is a highly individual matter, even among young children. (84) Furthermore, far too many individuals of all ages are making poor choices day after day and are either now living with the consequences or will be in the future. Nutritionists and workers in allied professions have been concerned about helping people learn to select and enjoy a wide variety of food combinations that can add up to a good diet. Most people believe that they are well-fed—that the choices they make are good ones. After all, they are not really sick; neither are they hungry. However, their nutrition is really poor in one respect or another. Milk and milk products, such as cheese, icecream, buttermilk, and yogurt, are often neglected. Then people may leave out in their diets many fruits and vegetables, particularly those that are good sources of vitamins A and C. These include dark green, leafy vegetables; deep yellow vegetables; and citrus fruits and vegetables, such as cabbages, tomatoes, and green peppers.