Passage 17

Space is a dangerous place, not only because of meteors but also because of rays from the sum 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 kspacecraft, 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 no be discovered until the birth of deformed children or even grandchildren.

Missions of the Apollo flights have had to cross belts of high amount of rems. So far, no dangerous amounts of radiation have had to cross belts of high 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 beenfound so far.

81. According to the first paragraph, the atmosphere is essential to man in that_______

A) it protects him against the haumful 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

82. 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

83. The harm radiation has done to the Apollo crew members_____

A) is insignifiacant B) seems overestimated

C) is enormous D) remains unknown

84. 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

85. The best title for this passage would be _________

A) The Atmosphere and Our Environment B) Research on Radiation

C) Effects of Space Radiation D) Importance of Protection Against Radiation

Passage 17

宇宙是个危险的地方，不仅因为有流星，还因为来自太阳与其它星球的辐射。大气层实际上也起了地球保护毯的作用。光线可以穿过大气层，这一点对于植物为我们提供食用物品来说致关重要。热量也令我们的环境达到可以忍受的程度。各种来自外太空的射线穿过大气，但无数来自太阳的射线被遮蔽了。（８１）一旦人离开了大气，他们就会暴露在射线中，但如果他们穿着宇航服，或是在太空飞行物里，就会防止很多射线伤害。

辐射是宇宙中已知的对探险队员最大的危险。辐射的单位叫做“雷姆”。科学家推断人可以忍受远大于0.1雷姆的辐射而不受到伤害，60雷姆也可以。（８２）问题在于要判断是否受到射线伤害极为困难——一个人也许感觉状态极佳，他的细胞或她的性器官可能已受到损害了，而这要一直到生下畸形的子女或者甚至孙子女才会被发现。阿波罗号的飞行任务就必须在出发和返航的路上都穿过高辐射地带，阿波罗全体宇航员积累了大量雷姆。（８３）迄今为止，还没有辐射危害数量的报告，但阿波罗号的飞行任务时间相当短。我们只是不明白人们是怎样可以在大气保护层之外的太空实验室工作数周或数月。（８４）药物也许有助于减小辐射带来的伤害。但至今还没发现真正有效的药物。

８１、根据第一段，大气对人至关重要是在于_______

Ａ）它保护人不受来自太空的有害射线伤害

Ｂ）它为植物生长提供足够的光线

Ｃ）它提供人类生存所必需的热量

Ｄ）它遮蔽落下的流星

８２、我们由本文可知_________

Ａ）暴露于哪怕数量极小的辐射中也是致命的

Ｂ）暴露在射线中的后果要比较长时间才看得出

Ｃ）在宇宙探险时可以避开辐射

Ｄ）穿着宇航服的宇航员不必担心辐射伤害

８３、阿波罗号的船员已经受到的有害辐射________

Ａ）无关紧要　　　　　Ｂ）似乎过分估计了　　　Ｃ）很大　　　Ｄ）还不清楚

８４、由本文可推出__________

Ａ）阿波罗号的飞行任务非常成功　　　

Ｂ）防止宇宙辐射不容易

Ｃ）宇航员会生下畸形的子女或孙子女

Ｄ）辐射对于完全受到保护的太空探险队员来说不构成威胁

８５、本文最好的标题应是__________-

Ａ）大气与环境　　　　　　　　　　　　　　Ｂ）对辐射的研究

Ｃ）太空辐射的后果　　　　　　　　　　　　Ｄ）保护人们防止辐射的重要性