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 __1__ our protective blanket on earth. Light gets through, and this is essential __2__ plants to make the food which we eat. Heat, __3__ , makes our environments tolerable and some ultraviolet rays (紫外线的) penetrate the atmosphere. Cosmic (宇宙的) rays of various kinds come __4__ the air from outer space, but a great quantity of radiation from the sun are screened off. __5__ men leave the atmosphere they are exposed to this radiation; but their spacesuits or the walls of their spacecraft, if they are inside, __6__ prevent a lot of radiation damage. Radiation is the greatest known danger to explorers in __7__ . Doses of radiation are measured in units called “rems (雷目)”. We all __8__ radiation here on earth from the sun, from cosmic rays and from radioactive minerals. The “__9__” dose of radiation that we receive each year is about two milligrams; it __10__ according to where you live, and this is a very rough estimate.
1. A. for B. with C. on D. as
2. A. with B. from C. under D. for
3. A. again B. also C. besides D. too
4. A. across B .to C. from D. through
5. A. As soon as B. As well asC. As much as D. As possible as
6. A. get B. make C. have D. do
7. A. earth B. atmosphere C. space D. environment
8. A. receive B. accept C. bring D. catch
9. A. conventional B. commonC. general D. normal
10. A. shifts B. converts C. modifies D. varies
1.【答案】D （北京安通学校提供）
【解析】act as “充当、起……作用”；act for “代表、代理”；act on “按照”。本句意为大气层起到保护伞的作用。
2.【答案】D
【解析】be essential for “对……来说是首要的、基础的”，固定搭配。
3【答案】D
【解析】本句意为：热不仅使我们的生产环境温度适宜，而且紫外线也能穿透大气。also一般紧跟动词；besides一般用在句前；too可用在句中，用逗号隔开。
4.【答案】D
【解析】这里的come through相当于penetrate，穿透。come across “偶遇”；come to “来到”；come from “来自”。本句意为：各类来自外部空间的宇宙射线穿透大气层……，故选come through。
5.【答案】A
【解析】as soon as “只要”；as well as “除……之外”；as much as “和……一样多”；as possible as “尽可能的”。
6.【答案】D
【解析】do +动词原型的结构表示强调谓语动词。
7.【答案】C
【解析】由radiation和explorers可推测，应选space (太空)。本句意为射线是探险者在太空遇见的已知的最大危险。
8.【答案】A
【解析】receive表示客观收到；accept表示主观接受。我们受到的辐射并非主观接受。
9.【答案】D
【解析】conventional “传统的”；common “共同的、普通的”；general “一般的、总体的”；normal “正常的”。本句意为：我们每年接受的正常辐射量……，故选normal。
10.【答案】D
【解析】shift “移动”；convert “转换”；modify “修改”；vary “变化”。根据句意，所处地点不同，所受辐射量也不一样……，故选varies |
