2. 外语
  3. 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

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

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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【C1】______our protective blanket on【C2】______. Light gets through, and this is essential【C3】______plants to make the food which we【C4】______. Heat,【C5】______, makes our environments tolerable and some ultraviolet rays(紫外线)penetrate the【C6】______. Cosmic(宇宙的)rays of various kinds come【C7】______the air from outer space, but【C8】______quantities of radiation from the sun are screened off. As【C9】______as men leave the atmosphere they are【C10】______to this radiation;【C11】______their spacesuits or the walls of their spacecraft, if they are inside,【C12】______prevent a lot of radiation damage.
    Radiation is the greatest known danger to explorers in【C13】______. Doses of radiation are measured in【C14】______called "rems(雷姆)". We all【C15】______radiation here on earth from the sun, from cosmic rays and from radioactive minerals. The "【C16】______"dose of radiation that we receive each year is about 100 millirems; it【C17】______according to where you live, and this is a very rough estimate. Scientists have reason to think【C18】______a man can【C19】______up with far more radiation【C20】______this without being damaged; the figure of 60 rems has been agreed.
【C18】
选项 A、what
B、which
C、that
D、why
答案C
解析 逻辑衔接题。该从句并不缺少句子成分，故排除what和which；语法上看why和that都可以，这就要从意思及逻辑上判断。此句和下一句间用的是分号，分析它们之间的关系。下旬中有60 rems，而之前有提到100 millirems再看本句，不难发现far more radiation______ this正是这两个数字的比较。也就是分号后的句子只是对分号前信息的进一步说明即为什么是far more，而不是讲have reason to think的原因，故选C。
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