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

Space is dangerous place, not only because of meteors(流星)but also because of rays from the sun and other Stars. The atmosphere a

admin2010-10-14  49
问题     Space is dangerous place, not only because of meteors(流星)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 spacesuits 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(畸形的)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 outside the protection of the atmosphere, working in a space laboratory. Drugs might help to decrease the damage done by radiation, but no really effective ones been found so far.
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 主题题型。文章开头就说太空危险是因为辐射，接着说人离开大气层就会受到辐射的危害，然后说造成危害的辐射量和后果在短期内难以察觉，最后说真正有效的减轻辐射的药物还没有找到。文章主要谈论的是太空辐射的后果。比较四个选项，选项C“太空辐射的影响”最能概括文章的内容，为正确答案。
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