Space is a dangerous place, not only because of meteors (流星) but also becaus

游客2025-03-24 30

问题 Space is a 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 have been found so far. [br] 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

解析本题问这篇文章的最佳标题是什么。通读全文内容，抓住文章的主旨，我们就可找出本题的正确答案C。文章虽然谈及“大气层”、“环境”、“辐射”、“防护辐射”等，但都不是文章谈论的主旨。文章开宗明义地谈及太空之所以危险主要是辐射，接着谈论人离开大气层就会受到辐射的危害，再接下来谈论造成危害的辐射量和辐射危害在短期内难以察觉，最后提到药物可以减轻辐射危害，但真正有效的药物还没有发现。因此不难看出文章主要谈论的是太空辐射的影响。因此，本题的正确答案应是C。

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