单选题Visiting a National Park can be relaxing, inspiring, but it can also be disturbing. As you drive into Rocky Mountain National Park, and you will see starving elk, damaged meadows and dying forests. Our parks are growing old because we have mistakenly protected them from natural processes, such as fire, predation, and insects. We believed that we were saving these remnants of wild America, but actually we have "protected" them to death. If we want to save our National Parks, the National Park Service must change its management priorities to prevent over population of animals and to restore natural process in the forest in order to prevent their stagnation and "death" by old age. We must act soon: our parks are dying of old age because we have altered the forces in nature that keep them young and strong. By tracing the history of our National Parks, we can understand the problem and see why we need active management. In the early part of the 20th century, settlers exploited wildlife heavily, resulting in neat-extinction of many species. Therefore, several National Parks were established by Congress primarily to save endangered animals. However, stricter wildlife protection laws and improved wildlife management techniques resulted in greater populations of animals overcrowding in areas of high concentration, such as the Yellowstone elk herds. Complicating the problem, the National Park Service in the early part of the 20th century adopted a policy of aggressive predator elimination, thus reducing natural wildlife population control. Subsequently, elk and deer populations exploded in many National Parks, resulting in severe damage to native vegetation. Vigorous forest fire and insect suppression in the National Parks through out the 20th century further altered the natural environment by allowing forests t6 over-mature, without natural thinning processes. Park managers thought that they were protecting the land, but actually they were removing important controls from the forest ecosystems. Clearly, we must act immediately if we want to pass down to our children and grandchildren the green legacy of our National Parks: we must step in and restore the natural processes which we have altered through our well-intentioned, but misguided, policies in the past.

单选题Every object in the universe,______large or small, has a tendency to move towards every other object.

单选题In the last few minutes the conversation has become seemingly ______ as if the discussion were of some minor domestic matter and not survival itself.(2003年3月中国科学院考博试题)

单选题Within the bounds of given data, the biographer seeks to illuminate factual information about a person and transform it into insight.

单选题Artists in the period of Renaissance had the advantage of being able to study Roman and Greek literature and sculpture because ______.

单选题Her written English was wonderful, and she had a (n) ______ vocabulary for a freshman.

单选题The meal he served to the guests was rather ______.

单选题Both parties promised to ______ the contract to be signed the following day. A. keep with B. tangle with C. adhere to D. devote to

单选题In calculating the daily calorie requirements for an individual, variations in body size, physical activity and age should be______.

单选题Mary Robinson has been formally ______ as Ireland's first woman president.

单选题{{B}}Passage 3{{/B}} When you are small, all ambitions fall into one grand category: when I'm grown up. When I'm grown up, you say, I'll go up in space. I'm going to be an author. I'll kill them all and then they'll be sorry. I'll be married in a cathedral with sixteen brides- maids in pink lace. I'll have a puppy of my own and no one will be able to take him away. None of it ever happens, of course, of dam little but the fantasies give you the idea that there is something to grow up for. Indeed one of the saddest things about gild-ed adolescence is the feeling that from eighteen on, it's all downhill; I read with horror of an American hippie wedding where someone said to the groom (age twenty) 'you seem so kinda grown up somehow', and the lad had to go around seeking reassurance that he wasn't, no, early he wasn't. A determination to be better adults than the present incumbents is fine, but to refuse to grow up at all is just plain unrealism. Right, so then you get some of what you want, or something like it or something that will do all right; and for years you are too busy to do more than live in the present and put one foot in front of the other; your goals stretching little beyond the day when the boss has a stroke or the moment when the children can bring you tea in bed and the later moment when they actually bring you hot tea, not mostly clopped in the saucer. However, I have now discovered an even sweeter category of ambition. When my children are grown up I'll learn to fly an aero plane. I will career round the sky, knowing that if I do go pop there will be no little ones to suffer shock and maladjustment; that even if the worst does come to the worst I will at least dodge the geriatric ward and all that looking for your glasses in order to see where you've left your teeth. When my children are grown up I'll have fragile, lovely things on low tables; I'll have a white carpet; I'll go to the pictures in the 'afternoon. When the children are grown up I'll actually be able to do a day's work in day, instead of spread over three, and go away for a weekend without planning as if for a trip to the Moon. When I'm grown up--I mean when they're grown up--I'll be free. Of course, I know it's got to get worse before it gets better. Twelve-year-olds, I'm told, don't go to bed at seven, so you don't even get your evenings; once they're past ten you have to start worrying about their friends instead of simply shooting the intruders off the doorstep, and to settle down to a steady ten years of criticism of every- thing you've ever thought or done or won. Boys, it seems, may be less of a trial than girls since they can't get pregnant and they don't borrow your clothes--it they do borrow your clothes, of course, you've got even more to worry about. The young don't respect their parents any more, that's what. Goodness, how sad. Still, like eating snails, it might be all right once you've got over the idea: it might let us off having to bother quite so much with them when the time comes. But one is simply not going to be able to drone away one's days, toothless by the fire, brooding on the past.

单选题Our research has focused on a drug which is so ______ as to be able to change brain chemistry. A. powerful B. influential C. monstrous D. vigorous

单选题Most scholars agree that Isaac Newton, while formulating the laws of force and gravity and inventing the calculus in the late 1600s, probably knew all the science there was to know at the time. In the ensuing 350 years an estimated 50 million research papers and innumerable books have been published in the natural sciences and mathematics. The modern high school student probably now possesses more scientific knowledge than Newton did, yet science to many people seems to be an impenetrable mountain of facts. One way scientists have tried to cope with this mountain is by becoming more and more specialized. Another strategy for coping with the mountain of information is to largely ignore it. That shouldn't come as a surprise. Sure, you have to know a lot to he a scientist, but knowing a lot is not what makes a scientist. What makes a scientist is ignorance. This may sound ridiculous, but for scientists the facts are just a starting place. In science, every new discovery raises 10 new questions. By this calculus, ignorance will always grow faster than knowledge. Scientists and laypeople alike would agree that for all we have come to know, there is far more we don't know. More important, every day there is far more we know we don't know. One crucial outcome of scientific knowledge is to generate new and better ways of being ignorant: not the kind of ignorance that is associated with a lack of curiosity or education but rather a cultivated, high-quality ignorance. This gets to the essence of what scientists do: they make distinctions between qualities of ignorance. They do it in grant proposals and over beers at meetings. As James Clerk Maxwell, probably the greatest physicist between Newton and Einstein, said, "Thoroughly conscious ignorance...is a prelude to every real advance in knowledge. " This perspective on science—that it is about the questions more than the answers— should come as something of a relief. It makes science less threatening and far more friendly and, in fact, fun. Science becomes a series of elegant puzzles and puzzles within puzzles— and who doesn't like puzzles? Questions are also more accessible and often more interesting than answers; answers tend to be the end of the process, whereas questions have you in the thick of things. Lately this side of science has taken a backseat in the public mind to what I call the accumulation view of science—that it is a pile of facts way too big for us to ever hope to conquer. But if scientists would talk about the questions, and if the media reported not only on new discoveries but the questions they answered and the new puzzles they created, and if educators stopped trafficking in facts that are already available on Wikipedia—then we might find a public once again engaged in this great adventure that has been going on for the past 15 generations.

单选题Smith failed to ______ for the deficit in the company's bank balance.

单选题When I try to understand ______ that prevents so many Americans from being as happy as one might expect, it seems to me that there are two causes. A. why it does B. what it does C. what it is D. why it is

单选题We learn from the second paragraph that ______.

单选题The experiment long proved that X-rays cannot______lead.