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
51
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.
The harm radiation has done to the Apollo crew members ______.
选项
A、is significant
B、seems overestimated
C、is enormous
D、remains unknown
答案
D
解析
从文章中我们得知,到现在为止还没有报告显示阿波罗号受到辐射损害,所以A,B, C选项均与文章意思相悖,只有D相对正确。
转载请注明原文地址:https://kaotiyun.com/show/Fyt7777K
0
大学英语四级
相关试题推荐
A、He/Shecanhaveitforafewhours.B、He/Shecanhaveitforsixhours.C、He/Shecanhaveitforasingleday.D、He/Shecanha
A、Sheisateacher.B、Sheisastudent.C、Sheisalibrarian.D、Sheisashopassistant.CWhatisthewoman’sjobaccordingtot
Whatisthemainideaofthepassage?ThepassagestatesthattheSanAntonioprojectdifferedfromthoseinBostonandMinneap
A、Thecareerofanairhostess.B、Howtogoair-traveling.C、Theknowledgeofanaircraftindetail.D、Anewspaperadvertisement
Rugbyhasthereputationofbeingtheroughestsportsintheworld.OutsidetheBritishIsles,rugbyislittleknownand,infac
A、Itwasstolen.B、Itwasgivenaticket.C、Shecouldn’tfindit.D、Shefoundittowedawaybythepolice.CWhathappenedtoher
A、Whenhechewsonhardfoods.B、Whenheeatsuphardfoods.C、Whenhedrinkssomethingcold.D、Whenhedrinkssomethinghot.CW
Oncearuralcountry,theUnitedStatesistodayahighlyurbanizedcountry,andthree-quartersofitscitizensnowliveintown
Accordingtothepassage,whatwillmostexcellentseniorexecutivesdowhentheytacklecomplicatedproblems?Thelastsentenc
A、Chicken.B、Potatochips.C、Dessert.D、Drinks.C
随机试题
Thephonemesofalanguagecannotbestrungtogetherinanyrandomordertoformwords.Thephonologicalsystemdetermineswhich
[2003年第116题]一般二等人员掩蔽所的战时主要出入口,应有下列哪项配套设施?
某项目年设计生产能力8万台,年固定成本1000万元,预计产品单台售价500元,单台产品可变成本275元,单台产品销售税金及附加为销售单价的5%,则项目盈亏平衡点产量为()万元。
在纸币制度下,影响汇率变动的因素不包括()。
一般资料:男,28岁,公司职员。案例介绍:求助者是一名房地产销售人员,他所在组是该部门业绩最好的一个组,而且求助者的业绩也非常好,多次受到部门经理的表扬。可是上个月因为自己一时大意,谈失了一笔订单,业绩落后了很多。被组长知道后,狠批了他一顿,说他
下列关于观察的叙述正确的是()。
遗传变异与物种演化是生物界中存在的普遍现象,这种现象产生的原因是:
She______SouthAmericaattheageof15andhasneverreturned.
Suddenly,everywhereyoulook,everyone’stakingcoldshowers.Notliterally—thatwouldbeweird—butthere’snomistakingalif
A、Becausehe/shehasn’tseenyourCV.B、Becausehe/shewantstomakesureyouarenotlyingonyourCV.C、Becausehe/shewantst
最新回复
(
0
)