首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
Space is a dangerous place, not only because of meteors (流星) but also because of rays from the sun and other stars. The atmosphe
Space is a dangerous place, not only because of meteors (流星) but also because of rays from the sun and other stars. The atmosphe
admin
2010-02-20
40
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 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 rem without being damaged; the figure of 60 reins has been agreed on. The trouble is that it is extremely difficult to be sure about radiation damagea person may feel perfectly well, but the cells of his or her sex organs may be damaged, and this will no be discovered until the birth of deformed children or even grandchildren.
Missions of the Apollo flights have had to cross belts of high amount of rems. So far, no dangerous amounts of radiation have been reported, but the Apollo missions have been quite short. We simply do not know yet how men are going to get on when they spend weeks and months outside the protection of the atmosphere, working in a space laboratory. Drugs might help to decrease the damage done by radiation, but no really effective ones have been found so far.
According to the first paragraph, the atmosphere is essential to man in that ______.
选项
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
答案
A
解析
问题问的是为什么大气层对人类是至关重要的。文章的第四句说到了大气层屏蔽了大量的外来射线。
转载请注明原文地址:https://kaotiyun.com/show/Tyt7777K
0
大学英语四级
相关试题推荐
A、Hewasasoldier.B、Hewasablacksmith.C、Hewasasilversmith.D、Hewasateacher.CHowdidPaulRevereearnaliving?
A、ToputthehomeworkonDon’sdesk.B、ToleavethemasterkeyforDon.C、TogiveDon’sstudentsthenextassignmeat.D、Tocall
Thepassageintroducessomekindsoftaxesandthefactorstojudgeatax.Apersonwhoreceivestheinheritanceneedstopayf
Supposeyouarestudyingatauniversitywhichoffersscholarshipstothosestudentswhoseaveragemarkisover90.Yourrecord
What’sthemaintopicofthepassage?Ifapoorcountrymanagedtoprovideenoughfoodforchildren,theyearlyeconomicgrowth
Ifyouknowexactlywhatyouwant,thebestroutetogetajobistogetspecializedtraining.Arecentsurveyshowsthatcompan
A、Itisbig.B、Itissmall.C、Itispoor.D、Itisquiet.BWhatdoyouknowofthespeaker’sfamily?
TheUnitedStatesis【B1】anEnglishspeakingcountry.The【B2】ofthepopulationspeaksEnglishastheirnativelanguage.Business,
Nomatterhowlargeornotable(著名的)theU.S.travelindustryisormaybecome,itwillalwaysbemembersofabroaderworldsoci
A、Itbuildsnewoilfacilities.B、Itpaysbacktoitscitizens.C、Itgivesbenefitstolargecorporations.D、Itpaysbacktothe
随机试题
7岁男孩,晨起眼睑水肿伴尿少1周,发现肉眼血尿1天,病前7天有“咽痛”。体查:体温38.0℃,血压120/80mmHg,发育营养好,双侧扁桃体Ⅱ度肿大。外周血示血红蛋白112g/L;尿常规示蛋白++/HP,红细胞+++/HP,白细胞1~4/HP,比重:1.
设函数y=f(x)由方程xy一2x+2y=0确定,那么f’(0)=__________.
少尿是指
甲被一车撞倒昏迷在路旁,肇事车主驾车逃跑。乙路过见状将甲送往医院抢救,支出医疗费若干元。在救助过程,乙身穿的名牌T恤被血染了,无法使用。则乙可以向甲主张哪些权利?()
根据有关税收法律、法规的规定,以下需要办理税务登记的是()。
A公司于2007年1月1日将一幢商品房对外出租并采用公允价值模式计量,租期为3年,每年12月31日收取租金100万元,出租时,该幢商品房的成本为2000万元,公允价值为1900万元,2007年12月31日,该幢商品房的公允价值为2100万元。A公司2006
aCxsFbycxFdyAe
谢恩归纳分类的人类的假设包括()的假设。
如图是A、B两种物质的溶解度曲线,下列说法正确的是:
Wedebatedtheadvantagesanddisadvantagesoffilmingfamousworks______intendedforthetheater.
最新回复
(
0
)