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听力原文：W: Do you need any more books from the library？
M: Yes, please. Can you get me one about computer science？ I've just finished this one about natural science.
Q: What book does the man want from the library？
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Traveling can be fun mad easy. A vacation trip to another part of the country is especially 【C1】______when the traveling conditions are good. Good traveling conditions【C2】______a comfortable and familiar mode of transportation, knowledge of the【C3】______language and system of money, with the customs and habits of the people in the country, 【C4】______ , and nice travel【C5】______. All of us have had nice trips like this. We have good【C6】______of an enjoyable, relaxing trip.
Most of us have also had trips that we would【C7】______to forget. Many conditions can produce a had【C8】______experience. For example, if the four conditions【C9】______above do not【C10】______, we will probably have a had experience, or a difficult【C11】______. Students who travel to【C12】______country to study often have a difficult trip. They usually travel【C13】______, they don' t know the language of the new country【C14】______, they are not familiar with the money system and so on. They often arrive in the new country at a huge 【C15】______airport. From the airport they need to【C16】______their way to the City where their school is. Maybe they need to【C17】______airplanes to take a bus, a train, or a taxi. They need to do all this in a country【C18】______everything is unfamiliar: the language, the money, the people, the cities, and the weather. Later, after the experiences are【C19】______, they can laugh. But at the【C20】______, they feel terrible.
【C1】
A．The man was an honest man.B．The man was a tricky man.C．The man was a bad man.D．The m
A．People think too much of their appearance.B．There is not a sure way of losing weight
Women live longer than men because they are spoiled for choice. That is the startling conclusion of an international group of scientists who say they have found the cause of female longevity.
They say females have two separate cell lines in their bodies, while men have only one. Women in old age can "choose" the more robust (强壮的) of these lines and survive for many more years.
Why there should be such a persistent cross-cultural gap between the life spans of the sexes has baffled scientists until now. In a paper in the journal Blood, and reported in the current issue of New Scientist, researchers at Odense University in Denmark and Ulleval University Hospital in Norway point to a key difference in the sex-determining chromosomes (染色体) found in the cells of men and women.
Every cell in a woman's body has two X chromosomes, one inherited from her mother and the other from her father. In each cell, one of these two X chromosomes is switched off. This means that a woman is a mosaic (混合体) of two cell lines: one derived from her father's X chromosome, the other from her mother's. By contrast, every cell in a man's body has an X and a Y chromosome, neither of which is turned off. He has only one cell line. This difference could be crucial in determining the long-term health of men and women, scientists concluded, and so they decided to examine cells taken from young women.
They found an even division between their two different lines. However, when they looked at elderly females they found their bodies now favoured one set of cells at the expense of the other line. "This suggests that one of the cell lines is 'better' than the other," say the researchers. In other words, women's bodies may select the more vigorous of the two cell lines and allow it to predominate the twilight of their years, giving them a crucial advantage over men, who have no chance of choosing the healthier of two sets of cells.
Women enjoy a longer life than men because______.
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