单选题

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.

单选题 According to the first paragraph, the atmosphere is essential to man in that______。
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

【正确答案】 A

【答案解析】[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。

单选题 We know from the passage that______.
A. exposure to even tiny amounts of radiation is fatal
B. the effect of exposure to radiation is slow in coming
C. radiation is avoidable in space exploration
D. astronauts in spacesuits needn't worry about radiation damage

【正确答案】 B

【答案解析】[解析] 本题考查考生归纳总结文章论点的能力。考的是从文章中我们能够了解的论点。选项A：暴露于数量极小的辐射中也是致命的，这与文章不符，因为第二段第二句话 (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 rem has been agreed on.)谈到人们能够承受一定量的辐射。选项C：在宇宙探险时可以避开辐射，这也与文章不符，因为文章第二段第一话(Radiation is the greatest known danger to explorers in space.)谈到辐射是宇宙中已知的对探险队员的最大的危险。选项D：穿着宇航服的宇航员不必担心辐射伤害，与文章也不符，第一段最后一句话(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.)谈到人们穿着宇航服，就会防止很多射线伤害，但并不等于没有伤害。选项B：暴露在射线中的后果要比较长的时间才看得出来，与文章第二段一致。所以，正确答案是B。

单选题 The harm radiation has done to the Apollo crew members______.
A. is insignificant
B. seems overestimated
C. is enormous
D. remains unknown

【正确答案】 D

【答案解析】[解析] 本题考查考生把握细节的能力。考的细节是有关辐射对阿波罗飞船上的宇航员造成的伤害。本题的答案可从文章第二段倒数第三句话 (So far, no dangerous amounts of radiation have been reported，but the Apollo missions have been quite short.)找到。所以，正确答案是D。

单选题 It can be inferred from the passage that______.
A. the Apollo mission was very successful
B. protection from space radiation is no easy job
C. astronauts will have deformed children or grandchildren
D. radiation is not a threat to well-protected space explorers

【正确答案】 B

【答案解析】[解析] 本题考查考生的逻辑推断能力。要求考生读完全篇文章之后做出合理的推断。选项A：阿波罗号的飞行任务非常成功，文章没有涉及。选项C：宇航员将会生下畸形的子女或孙子女，这与文章中心观点不符，文章谈到宇航员的生殖细胞有可能受到伤害，可能会导致畸形后代的出现。选项D：辐射对于完全受到保护的太空探险员来说不构成威胁。这与文章第二段第一句话(Radiation is the greatest known danger to explorers in space.)不符。从文章可以看出，迄今为止，还没有辐射危险量的报告，也还没发现真正有效减少辐射危害的药物，防止太空辐射的确不是一件容易的工作。所以，正确答案是B。