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

Radiation Effect Space is a dangerous place, not only because of meteors (流星)but also because of rays from the sun and other

admin2012-09-10  20
问题                           Radiation Effect
    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 that 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 spacecrafts, 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" (“雷姆”). 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 reins 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 larger amount of reins. 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 clone by radiation , but no really effective ones have been found so far.  
According to the first paragraph, the atmosphere is essential to man in that______。
选项 A、it protects him against the harmful rays from space
B、it provides sufficient light for plant growth
C、it supplies the heat necessary for human survival
D、it screens off the falling meteors
答案A
解析 本题考查考生的总结能力。考的是大气对人类至关重要的原因。它涉及 到第一段的主要内容。根据第一段我们得知，大量射线从外层空间透过大气层照射到地球上来，不过大量的太阳辐射波被大气层反射了。一旦人们离开了大气层，就会直接暴露在太阳的辐射之下，但如果他们穿着宇航服，或是呆在航天器内，就会防止很多射线的伤害。所以，正确答案是A。
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