| Space is a dangerous place, not only
because of meteors 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 ream without being damaged; the figu 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 [单项选择]
Space is a dangerous place, not only because of meteors (流星) but also (1) rays from the sun and other stars. The atmosphere again (2) as our protective blanket on earth. Lightgets through, and this is essential for plants to (3) the food which we eat. Heat, too, makes our environment endurable. Various kinds of rays come through the air (4) outer space, but enormous quantities of radiation from the sun are (5) off. As soon as men leave the atmosphere they are (6) to this radiation, but their space suits or the walls of their spacecraft, if they are inside, (7) prevent a lot of radiation damage. (8) is the greatest known danger to explorers in space. The unit of radiation is called "rem". Scientists have (9) to think that a man can (10) far more radiation than 0.1 ram without being damaged: the figure of 60 rems has been agreed on. The trouble is that it is extremely difficult to make (11) about 我来回答: 提交
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