单选题John boasted that he could finish the job all by himself in no time.

单选题In the face of the evidence, the criminal had to______ his guilt to the court. A. admit B. acknowledge C. accept D. confess

单选题The protest went ahead despite government assurances that they would press for______with the neighboring country in the issuing of visas.

单选题The need for solar electricity is clear, it is safe, ecologically sound, efficient, continuously available, and is has no moving parts. The basic problem with the use of solar photovoltaic devices is economics, but until recently very little progress has been made toward the development of low-cost photovoltaic devices. The larger part of research funding has been devoted to study of single-crystal silicon solar cells, despite the evidence, including that of the leading manufacturers of crystalline silicon, that the technique holds little promise. The reason for this pattern is understandable and historical. Crystalline silicon is the active element in the very successful semiconductor industry, and virtually all of the solid state devices contain silicon transistors and diodes. Crystalline silicon, however, is particularly unsuitable to terrestrial solar cells. Crystalline silicon solar cells work well and are successfully used in the space program, where cost is not an issue. While single crystal silicon has been proven in extraterrestrial use with efficiencies as high as 18 percent, and other more expensive and scarce materials such as gallium arsenide can have even higher efficiencies, costs must be reduced by a factor of more than 100 to make them practical for commercial use. Beside the fact that the starting crystalline silicon is expensive, 95 percent of it is wasted and does not appear in the final device. Recently, there have been some imaginative attempts to make polycrystalline and ribbon silicon, which are lower in cost than high-quality single crystals. But to date the efficiencies of these apparently lower-cost arrays have been unacceptably small. Moreover, these materials are cheaper only because of the introduction of disordering in crystalline semiconductors, and disorder degrades the efficiency of crystalline solar cells. This dilemma can be avoided hy preparing completely disordered or amorphous materials. Amorphous materials have disordered atomic structure as compared to crystalline materials. That is, they have only short-range order rather than the long-range periodicity of crystals. The advantages of amorphous solar cells are impressive. Whereas crystals can be grown as wafers about four inches in diameter, amorphous materials can be grown over large areas in a single process. Whereas crystalline silicon must be made 200 microns thick to absorb a sufficient, amount of sunlight for efficient energy conversion, only I micron of the proper amorphous materials is necessary. Crystalline silicon solar cells cost in excess of $100 per square foot, but amorphous films can be created at a cost of about 50 per square foot. Although many scientists were aware of the very low cost of amorphous solar cells, they felt that they could never be manufactured with the efficiencies necessary to contribute significantly to the demand for electric power. This was based on a misconception about the feature which determines efficiency. For example, it is not the conductivity of the material in the dark which is relevant, but only the photoconductivity, that is the conductivity in the presence of sunlight. Already, solar cells with efficiencies well above 6 percent have been developed using amorphous materials, and further research will doubtless find even less costly amorphous materials with higher efficiencies.

单选题 Things were never easy within the family. But at a time when the family was oriented toward the production of goods, which alone made the survival of its members possible, there was an obvious necessity and a rational basis for their living and working together. Dire necessity did not permit putting into question the very existence of the family, despite the great emotional demands living together made on each of its members. Today the main economic activities of the family are in the nature of consumption—however productive may be what some of its members do in society. And from an early age on, each member of the family could survive without its support—since society at large is ready to provide support. It is quite easy to put the existence of the family into question. This happens very frequently, not just as families separate, or fail to be formed, but also within families which to all outer appearance are still intact. But once the family needs seriously to justify its existence, it is no longer intact as a family in the old sense. The modern family, deprived of its ancient and firm basis in economic necessity, now tries to justify its existence through the emotional ties within it. These always were present, but they were a superstructure good or bad, over the solid foundation of necessity. With the foundation of necessity removed, the emotions either tend to run rampant or to wither away. The more a family tries to justify itself by means af the feelings existing within it, the stronger these are aroused, and the more easily and severely do they get hurt. There is more reason to wish to exculpate oneself, to wish that the blame for what goes wrong should rest with someone else. The young generation easily blames their parents for all the difficulties they encounter within themselves, society, and the family. Parents prefer to see all that is wrong ascribed either to the indifferent or otherwise nasty behavior of the new generation, to the destructive impact of the peer group, or of society at large. Which is preferred as the target to be blamed depends on the structure of the personality of the individual, the mood of the day, or the most recent headlines. In Civilization and Its Discontent Freud showed why civilization must exact a high price in psychological discomfort for the very great and real advantages it provides us: creating and maintaining a civilized life requires considerable and difficult repression and sublimation of many aspects of our selfish drives, although we would prefer them to find immediate gratification. How understandable, then, that as civilization imposes a considerable price in personal psychological frustration, the same is true for the family, out of which civilization grew. If this is so, why have we such a hard time accepting the frustrations and disappointments which are the unavoidable price we have to pay for living in families?. Why do we wish to blame the hardships of family living on something or somebody, even on ourselves, although blaming these difficulties on each other increases them beyond endurance?

单选题Questions 21—24 are based on the following monologue. You now have 15 seconds to read question 21—24.

单选题Before Columbus set sail on his first voyage of discovery, many pooh-poohed his chances, and were unwilling to ______ on his chances of success.

单选题At 7 o'clock tomorrow evening, I ______ a walk in the neighbourhood. So you won't find me at home then. A. shall take B. will take C. shall be taking D. am taking

单选题It's more difficult to solve a problem than______ A. a question is found B. finding a question C. that of finding a question D. to find a question

单选题There are quite a few people who are willing to prostitute their intelligence for a mess of pottage．

单选题In the ______ chapters, the professor has traced the redefinition of Britain's global position in recent decades. A. obsolete B. abiding C. preceding D. wielding

单选题According to the passage, a city's situation is more important than its site in regard to the city's ______.

单选题Some researchers feel that certain people have nervous systems particularly ______ to hot, dry winds. They are what we call weather-sensitive people.

单选题It looks like a great big cigar, (1) it is really a dangerous saltwater fish called barracuda. This (2) fish has a narrow body which grows to be from four to six feet long. However it may reach ten feet in (3) ! The barracuda looks very much (4) the pike, a freshwater fish. Although the barracuda is not related (5) the pike, it is like that freshwater fish in being a fearless fighter. The barracuda has a large mouth and strong jaws that hold knifelike (6) . When attacking or defending (7) the barracuda moves like lightning. It usually feeds on other fish. But it has been known to (8) swimmers. No wonder it is called "the tiger of the sea" ! The barracuda is usually found in warm, tropical seas or (9) . The most dangerous kind, the great barracuda, is found off the (10) of Florida, Bermuda, and the West Indies. (11) caught for food live in the warm waters off the coast of California and Australia. To (12) its enemies, the barracuda can camouflage itself. It does this by taking on the color of its (13) . Its back changes from light brownish green (14) deep blue, its sides sparkle with silvery tones, and its belly is chalky white. The barracuda's tail and fins may be greenish yellow or gray. Bright eyes flash as it roams the (15) . When it rests on the sandy ocean floor, it becomes ahnost (16) as long as it stays quite still. Even when it prowls around a coral reef, it is difficult to spot, even in (17) water. People who (18) for sport try to excite the barracuda to move by tying a long, white rag behind their moving boat. However, they are often (19) . But they never give up trying to trick "the (20) of the sea/

单选题Just over a year ago, I foolishly locked up my bicycle outside my office, but forgot to remove the pannier. When I returned the pannier had been stolen. Inside it were about ten of the little red notebooks I take everywhere for jotting down ideas for articles, short stories, TV shows and the like. When I lost my notebooks, I was devastated; all the ideas I"d had over the past two years were contained within their pages. I could remember only a few of them, but had the impression that those I couldn"t recall were truly brilliant. Those little books were crammed with the plots of award-winning novels and scripts for radio comedy shows that were only two-thirds as bad as the ones on at the moment. That"s not all, though. In my reminiscence, my lost notebooks contained sketches for many innovative and incredible machines. In one book there was a design for a device that could turn sea water into apple cider; in another, plan for an automatic dog; in a third, sketches for a pair of waterproof shoes with television screens built into the toes. Now all of these plans are lost to humanity. I found my notebooks again. It turns out they weren"t in the bike pannier at all, but in a bag in my spare room, where I found six months after supposedly losing them. And when I flipped through their pages, ready to run to the patent office in the morning, I discovered they were completely full of rubbish. Discovering the notebooks really shook me up. I had firmly come to believe they were brimming with brilliant, inventive stuff—and yet clearly they weren"t. I had deluded myself. After surveying my nonsense, I found that this halo effect always attaches itself to things that seem irretrievably lost. Don"t we all have a sneaking feeling that the weather was sunnier, TV shows funnier and cake-shop buns bunnier in the not-very-distant pasty. All this would not matter much except that it is a powerful element in reactionary thought, this belief in a better yesterday. After all, racism often stems from a delusion that things have deteriorated since "they" came. What a boon to society it would be if people could visit the past and see that it wasn"t the paradise they imagine but simply the present with different hats. Sadly, time travel is impossible. Until now, that is. Because I"ve suddenly remembered I left a leather jacket in an Indonesian restaurant a couples of years ago, and I"m absolutely certain that in the inside pocket there was a sketch I"d made.

单选题Traditional fairytales are being ditched by parents because they are too ______ for their young children, a study found. A. scarce B. scary C. scared D. scarred

单选题Curiosity and discontent are deep human urges which work together to ______ all human discovery and achievements.

单选题Some workers in the nuclear power station were exposed to high levels of ______ .

单选题Although Barbara argues strongly that current policies are unjust, she does not ______any particular changes.