单选题He (failed in) the competition, (that) (proved) that he was not working (hard enough).

单选题A study by scientists in Finland has found that mobile phone radiation can cause changes in human cells that might affect the brain, the leader of the research team said. But Darius Leszczynski, who headed the 2-year study and will present findings next week at a conference in Quebec, said more research was needed to determine the seriousness of the changes and their impact on the brain or the body. The study at Finland's Radiation and Nuclear Safety Authority found that exposure to radiation from mobile phones can cause increased activity in hundreds of proteins in human cells grown in a laboratory, he said. "We know that there is some biological response. We can detect it, with our very sensitive approaches, but we do not know whether it can have any physiological effects on the human brain or human body," Leszczynski said. Nonetheless the study, the initial findings of which were published last month in the scientific journal Differentiation, raises new questions about whether mobile phone radiation can weaker/the brain's protective shield against harmful substances. The study focused on changes in cells that line blood vessels and on whether such changes could weaken the functioning of the blood-brain barrier, which prevents potentially harmful substances from entering the brain from the bloodstream, Leszczynski said. The study found that a protein called hsp27 linked to the functioning of the bloodbrain barrier showed increased activity due to irradiation and pointed to a possibility that such activity could make the shield more permeable, he said. "Increased protein activity might cause cells to shrink--not the blood vessels but the cells themselves—and then tiny gaps could appear between those cells through which some molecules could pass." he said. Leszczynski declined to speculate on what kind of health risks that could pose, but said a French study indicated that headache, fatigue and sleep disorders could result. "These are not life-threatening problems but can cause a lot of discomfort," he said, adding that a Swedish group had also suggested a possible link with Alzheimer's disease. "Where the truth is I do not know," he said. Leszczynski said that he, his wife and children use mobile phones, and he said that he did not think his study suggested any need for new restrictions on mobile phone use.

单选题Animals have different ways of protecting themselves against wintertime weather. Some animals grow heavy coats of fur or feathers, while others dig into the ground to find a warm wintertime home. Some animals spend the winter in a deep sleep because by going to sleep they avoid the time of the year when food is scarce and the temperatures are low. Their sleep is known as hibernation. There is much about hibernation that puzzles scientists. For example, they are wondering how hibernation came into being. Some scientists have explored the possibility that animals release a chemical that starts them hibernating. One thing that scientists are certain about is that animals hibernate only when it is cold. Hibernation is a seasonal practice. Some animals that fall into a wintertime sleep are not true hibernators because they spend only a part of the cold season asleep. Bears, for example, can easily be awakened from their winter nap. They are not true hibernators. Sometimes it is difficult to determine whether a particular animal is a true hibernator. For example, some mice hibernate, but others do not. The same is true of bats. Some of them hibernate. Others do not.

单选题Suddenly one of the leaves begins to fly in a strong wind; the leaf is really no leaf at all--it's an insect ______ as a leaf.

单选题______ leisure was generally considered a waste of time.

单选题 The current emergency in Mexico City that has taken over our lives is nothing. I could ever have imagined for me or my children. We are living in an environmental crisis, an air-pollution emergency of unprecedented severity. What it really means is that just to breathe here is to play a dangerous game with your health. As patents, what terrorizes us most are reports that children are at higher risk because they breathe more times per minute. What more can we do to protect them and ourselves? Our pediatrician's (儿科医师的) medical recommendation was simple: abandon the city permanently. We are foreigners and we are among the small minority that can afford to leave. We arc here because of my husband's work. We are fascinated by Mexico--its history and rich culture. We know that for us, this is a temporary danger. However, we cannot stand for much longer the fear we feel for our boys. We cannot stop them from breathing. But for millions, there is no choice. Their lives, their jobs, their futures depend on being here. Thousands of Mexicans arrive each day in this city, desperate for economic opportunities. Thousands more are born here each day. Entire families work in the streets and practically live there. It is a familiar sight: as parents hawk goods at stoplights, their children play in the grassy highway dividers, breathing exhaust fumes. I feel guilty complaining about my personal situation; we won't be here long enough for our children to form the impression that skies are colored only gray. And yet the government cannot do what it must to end this problem. For any country, especially a developing Third World economy like Mexico, the idea of barring from the capital city enough cars, closing enough factories and spending the necessary billions on public transportation is simply not an option. So when things get bad, as in the current emergency, Mexico takes half measures--prohibiting some more cars from circulating, stopping some factories from producing--that even its own officials concede aren't adequate. The word "emergency" implies the unusual. But when daily life itself is an emergency, the concept loses its meaning. It is human nature to try to adapt to that which we cannot change or to mislead ourselves into believing we can adapt.

单选题He spoke in such a high voice ______ at the farther end of the room.

单选题More than a quarter of American children--and half of black children--belong to families too poor to fully qualify for the ＄1,000-a-year child tax credit, which President Bush signed four years ago and has cited in arguing that his program of sweeping tax cuts helps low-income families, a new study has found. With an annual value of $47 billion, the credit is the government's largest children's subsidy and one that has provoked sharp partisan fights. Many conservatives, viewing it solely as a tax cut, want to reserve the credit for families that owe federal income tax. Many liberals, vie-wing it as a broader children's allowance, want to extend it to poorer workers, who they say need it most. Still, the study found that the families of 19.5 million children were too poor to receive the full ＄1,000 benefit. About half get a partial benefit, and half get nothing. Newt Gingrich, the former Republican House speaker, expressed surprise at the racial gap. "That's a stunning number," he said, referring to the half of black children who fail to receive the full credit. "I'd find a way to make sure those kids get the money as part of a broader post-Hurricane Katrina plan." Framed as middle-class tax relief, the credit passed in 1997 and offered ＄500 per child to families that owed income tax. It was doubled in 2001 and made partly available to families too poor to have income tax bills. Len Burman, a co-director of the tax center and the study's author, said it might actually exaggerate the amount going to the poor since it assumed all eligible families received the credit. In practice, studies suggest that poor and minority families claim tax credits at lower rates. Told of the study, which will be published Monday, some conservatives repeated their opposition to making the credit more of an antipoverty program. Mr. Mitchell said that low-wage workers received a total of ＄39 billion a year from a similar program, the earned income tax credit. "It's not like they're not getting any redistribution from the government," he said. "We want less income redistribution, not more." Both sides in child tax credit debate have cast their arguments in moral terms. "The income gap is wide and growing," Ms. Snowe said. "We're talking about giving a helping hand to families who through no fault of their own are at or near poverty." Mr. Mitchell of the Heritage Foundation said income redistribution was morally problematic, since it punished people for economic success. He also called it economically inefficient, arguing that it discouraged work among both rich and poor.

单选题By the first decade of the 21st century, international commercial air traffic is expected ______ vastly beyond today"s levels.

单选题The doctors don't______that he will live much longer.

单选题 Music comes in many forms; most countries have a style of their own. {{U}}(1) {{/U}} the turn of the century when jazz was born, America had no prominent {{U}}(2) {{/U}} of its own. No one knows exactly when jazz was {{U}}(3) {{/U}},or by whom. But it began to be {{U}}(4) {{/U}} in the early 1900s. Jazz is America's contribution to {{U}}(5) {{/U}} music. In contrast to classical music, which {{U}}(6) {{/U}} formal European traditions, jazz is spontaneous and free-form. It bubbles with energy, {{U}}(7) {{/U}} the moods, interests, and emotions of the people. In the 1920, jazz {{U}}(8) {{/U}} like America. And {{U}}(9) {{/U}} it does today. The {{U}}(10) {{/U}} of this music are as interesting as the music {{U}}(11) {{/U}}. American Negroes, or blacks, as they are called today, were the jazz {{U}}(12) {{/U}}. They were brought to the Southern states {{U}}(13) {{/U}} slaves. They were sold to plantation owners and forced to work long {{U}}(14) {{/U}}. When a Negro died his friends and relatives {{U}}(15) {{/U}} a procession to carry the body to the cemetery. In New Orleans, a band often accompanies the {{U}}(16) {{/U}}. On the way to the cemetery the band played slow, solemn music suited to the occasion. {{U}}(17) {{/U}} on the way home the mood changed. Spirits lifted. Death had removed one of their {{U}}(18) {{/U}}, but the living were glad to be alive. The band played {{U}}(19) {{/U}} music, improvising on both the harmony and the melody of the tunes {{U}}(20) {{/U}} at the funeral. This music made everyone want to dance. It was an early form of jazz.

单选题Woman: Well, the income tax is too high for me this month. Man: If it were not reasonable, I"m afraid some people would try to get round the tax. Question: What does the man mean?

单选题The ______ of the rural world because of distance and the lack of transport facilities is compounded by the paucity of the information media. A. inaccessibility B. isolation C. penetration D. negligence

单选题"In every known human society the male's needs for achievement can be recognized. . . In a great number of human societies men's sureness of their sex role is tied up with their right, or ability, to practice some activity that women are not allowed to practice. Their maleness in fact has to be underwritten by preventing women from entering some field or performing some feat. " This is the conclusion of the anthropologist Margaret Mead about the way in which the roles of men and women in society should be distinguished. If talk and print are considered it would seem that the formal emancipation of women is far from complete. There is a flow of publications about the continuing domestic bondage of women and about the complicated system of defences which men have thrown up around their hitherto accepted advantages, taking sometimes the obvious form of exclusion from types of occupation and sociable groupings, and sometimes the more subtle form of automatic doubt of the seriousness of women's pretensions to the level of intellect and resolution that men, it is supposed, bring to the business of running the world. There are a good many objective pieces of evidence for the erosion of men's status. In the first place, there is the widespread postwar phenomenon of the woman Prime Minister, in India, Sri Lanka and Israel. Secondly, there is the very large increase in the number of women who work, especially married women and mothers of children. More diffusely there are the increasingly numerous convergences between male and female behaviour: the approximation to identical styles in dress and coiffure, the sharing of domestic tasks, and the admission of women to all sorts of hitherto exclusively male leisure-time activities. Everyone carries round with him a fairly definite idea of the primitive or natural conditions of human life. It is acquired more by the study of humorous cartoons than of archaelology, but that does not matter since it is not significant as theory but only as an expression of inwardly felt expectations of people's sense of what is fundamentally proper in the differentiation between the roles of the two sexes. In this rudimentary natural society men go out to hunt and fish and to fight off the tribe next door while women keep the fire going. Amorous initiative is firmly reserved to the man, who sets about courtship with a club.

单选题(2005)The scientists were waiting to see the problem_____.

单选题The biggest problem facing Chile as it promotes itself as a tourist destination to be reckoned ______, is that it is at the end of the earth. It is too far south to be a convenient way from the big tourist markets, unlike Mexico, for example.

单选题In learning a foreign language, ______ English, one should first pay attention to speaking, which is the groundwork of reading and writing. A. says B. say C. to say D. saying

单选题The discovery that, friction excluded, all bodies fall at the same rate is so simple to state and to grasp that there is a tendency to ______ its significance.