2. 外语
  3. Space is a dangerous place, not only because of meteors but also because of rays from the sun and other stars. The atmosphere ag

Space is a dangerous place, not only because of meteors but also because of rays from the sun and other stars. The atmosphere ag

admin2010-03-19  55
问题      Space is a dangerous place, not only because of meteors but also because of rays from the sun and other stars. The atmosphere again acts as our protective blanket on earth. Light gets through, and this is essential for plants to make the food which we eat. Heat, too, makes our environment endurable. Various kinds of rays come through the air from outer space, but enormous quantities of radiation from the sun are screened off. As soon as men leave the atmosphere they are exposed to this radiation but their space suits or the walls of their spacecraft, if they are inside, do prevent a lot of radiation damage.
     Radiation is the greatest known danger to explorers in space. The unit of radiation is called "rem". Scientists have reason to think that a man can put up with far more radiation than 0.1 rem without being damaged; the figure of 60 rems has been agreed on. The trouble is that it is extremely difficult to be sure about radiation damage—a person may feel perfectly well, but the cells of his or her sex organs may be damaged, and this will not be discovered until the birth of deformed children or even grandchildren. Missions of the Apollo flights have had to cross belts of high radiation and, during the outward and return journeys, the Apollo crew accumulated a large amount of rems. So far, no dangerous amounts of radiation have been reported, but the Apollo missions have been quite short. We simply do not know yet how men are going to get on when they spend weeks and months.
The best title for this passage would be ______.
选项 A、The Atmosphere and Our Environment
B、Research on Radiation
C、Effects of Space Radiation
D、Importance of Protection Against Radiation
答案C
解析 主旨判断题。本题要求根据文章内容为文章选择一个最适合的标题。由本文判断文章谈论的是“太空辐射的后果”，因此，C选项为正确答案。A项“大气层与我们的环境”只是在文章第一段谈到，所以不能概括全文的内容。从文章的行文可以看出，文章主要谈论辐射的危害，而非对辐射的研究，因此，B项不是正确答案。D项“保护人类免受太空辐射的重要性”也只是概括了文章的部分内容，不能作为全文的主题。
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