2. 外语
  3. Are we at the beginning of another Age of Exploration? Perhaps even more important, are we at the beginning of【C1】______ Age of

Are we at the beginning of another Age of Exploration? Perhaps even more important, are we at the beginning of【C1】______ Age of

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问题     Are we at the beginning of another Age of Exploration? Perhaps even more important, are we at the beginning of【C1】______ Age of Colonization? As the population of the world increases towards the point【C2】______ the earth can no longer support all the people【C3】______ on it, the second question becomes urgent. Will we discover a new world,【C4】______ Columbus did, on which human life will be possible? At this point in the space age, no one can really answer these questions. We can say,【C5】______ , that we will not see tomorrow the kind of space travel that【C6】______ fiction and the movies have shown. It will be a long time before we have flight that run【C7】______ to human colonies on the moon or on one of the planets. We are not even going to be able to【C8】______  immediate advantages of the minerals that we may find on the planets【C9】______ our own solar system.
    Great problems must be solved【C10】______ we could send colonies out into place. The distances that must be【C11】______ and the length of time it takes to do that can hardly be【C12】______ . There arc also dangers that we still do not really understand--from radiation, for example, or from pieces of matter  【C13】______ in space, or from contamination from forms of life that might【C14】______ there. There is also need for humans to take their own environment into space【C15】______ them. So far no "island" has been discovered in space on which people can exist without systems that【C16】______ life, and these systems must accompany any future space【C17】______  . Finally, on the most practical【C18】______ , there has to be enormous expense【C19】______ in space exploration. The U.S. and Russian governments have already spent billions of dollars for projects【C20】______ which they can receive a return only in knowledge and not in money.
【C10】
选项 A、after
B、till
C、before
D、until
答案C
解析 逻辑辨析题 根据句意，在进入太空前有一些问题需要解决，故选项C．before是正确答案。
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