首页
登录
职称英语
What forms of radiation are feared by astronauts? [br] [originaltext] Not l
What forms of radiation are feared by astronauts? [br] [originaltext] Not l
游客
2023-11-21
55
管理
问题
What forms of radiation are feared by astronauts? [br]
Not long ago it was assumed that the dangers man would meet in space would be terrible, the main ones being radiation and the danger of being hit by meteors. It is per- haps worth remembering that less than two centuries ago the dangers of train travel seemed similarly terrible. A man would certainly die, it was thought, if carried along at a speed of thirty kilometers per hour.
There are two sorts of radiation man must fear in space. The first is radiation from the sun, and this is particularly dangerous when the sun is very active and explosions are occurring on its surface. The second, less harmful form comes from the so-called Van Allen Belts. These are two areas of radiation about 1,500 miles away from the earth. Neither of these forms of radiation area is dangerous to us on the earth, since we are protected by our atmosphere. Specifically, it is that part of our atmosphere known as the ozonosphere which protects us. This is a belt of the chemical ozone between 12 and 21 miles from the ground, which absorbs all the radiation.
Once outside the atmosphere, however, man is no longer protected, and radiation can be harmful in a number of ways. A distinction must be drawn between the short-and long-term effects of radiation. The former are merely unpleasant, but just because an astronaut returning from a journey in space does not seem to have been greatly harmed, we cannot assume that he is safe. The long-term effects can be extremely serious, even leading to death.
选项
A、Between 12 and 21 miles
B、1,000 miles
C、150 miles
D、1,500 miles
答案
A
解析
“These are two areas of radiation about 1,500 miles away from the earth”,答案自然揭晓。
转载请注明原文地址:https://tihaiku.com/zcyy/3207290.html
相关试题推荐
Afghanistan’sfirstmatchwillbeagainst[originaltext] KualaLumpur-Afghanist
What’stheUSmilitary’sinvestigationon?[br][originaltext]TheUSmilitar
Whatdoesthespeakertalkabout?[br][originaltext]Innormalcircumstances
Whatdoesthespeakertalkabout?[originaltext]Innormalcircumstanceswolve
Howlonghastheprotestlastedaccordingtothenews?[br][originaltext]Mo
Howlonghastheprotestlastedaccordingtothenews?[br][originaltext]Mo
Wecaninferfromthespeakerthat[br][originaltext]Today,Iwanttotalk
Wecaninferfromthespeakerthat[br][originaltext]Today,Iwanttotalk
WhichofthefollowingstatementsisTRUEaboutLisa?[br][originaltext]W:Now
WhichofthefollowingstatementsisTRUEaboutLisa?[originaltext]W:Now,spec
随机试题
—IsthisTom’sdictionary?—No,it’s______.A、mineB、myC、meA名词性物主代词,表示“mydicti
Onedayalltheempolyeesofaveryfamouscompanyreachedtheirofficeanda
Therateatwhichmanhasbeenstoringupusefulknowledgeabouthimselfand
[img]2011q1/ct_etoefm_etoefspeaka_0222_20111[/img]Q:Describeasubjectthatyou
Alandfreefromdestruction,pluswealth,naturalresources,andlaborsupp
关于水泥混凝土配合比设计要求及设计方法,请回答以下问题。(1)水泥混凝土配合比设
平整度是路基路面施工质量检验的关键项目。()
甲公司2008年1月1日取得2000万元专门借款用于建造厂房,期限3年,借款利率
某混凝土试块强度值不满足规范要求,但经法定检测单位对混凝土实体强度经过法定检测后
某钢结构厂房在结构安装过程中,发现构件焊接出现不合格,施工项目部采用逐层深入排查
最新回复
(
0
)