The Chinese fairy story Flying to the Moon now turns to be true, with China【C1】______the country’s second unmanned lunar probe,

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问题     The Chinese fairy story Flying to the Moon now turns to be true, with China【C1】______the country’s second unmanned lunar probe, Chang’e 2 on 1st October, 2010. This mission marked another step for China’s pursuit of moon exploration. In fact, people all over the world have been and are【C2】______developing technologies for the exploration of deep space and the peaceful use of outer space, as space is actually 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【C3】______our protective blanket on【C4】______. Light gets through, and this is essential【C5】______plants to make the food which we【C6】______. Heat,【C7】______, makes our environments tolerable and some ultraviolet rays (紫外线的) penetrate the【C8】______. Cosmic (宇宙的) rays of various kinds come【C9】______the air from outer space, but【C10】______quantities of radiation from the sun are screened off.【C11】______men leave the atmosphere they are【C12】______to this radiation; 【C13】______their spacesuits or the walls of their spacecraft, if they are inside, 【C14】______prevent a lot of radiation damage. Radiation is the greatest known danger to explorers in【C15】______. Doses of radiation are measured in【C16】______called "rents (雷目)". We all【C17】______radiation here on earth from the sun, from cosmic rays and from radioactive minerals. The "【C18】______" dose of radiation that we receive each year is about two millirems; it【C19】______according to where you live, and this is a very rough estimate. Scientists have reason to think that a man can【C20】______far more radiation than without being damaged; the figure of 60 rems has been agreed.
【C18】

选项 A、conventional
B、common
C、general
D、normal

答案D

解析 句意理解。本句意为“我们每年接受的正常辐射量为千分之一雷目”,故normal正确,意为“正常的”。conventional意为“传统的”,common意为“共同的,普通的”,都不符合题意。general意为“一般的,总体的”,该词不太确切,该句不是指总体接受雷目情况,而是指正常情况,故不选。
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