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
A new kind of radar has been developed for spaceship travelers. A working laboratory model of a new system of radar that makes u
A new kind of radar has been developed for spaceship travelers. A working laboratory model of a new system of radar that makes u
admin
2009-01-15
60
问题
A new kind of radar has been developed for spaceship travelers. A working laboratory model of a new system of radar that makes use of a beam of light is said to be ten thousand times more accurate than the best comparable system of radar that uses microwaves.
The model has shown that this radar system, known as laser-dopple radar, can measure with absolute precision speeds varying from spaceship orbital injection(进入) velocities(速度) of five miles per second down to virtual stops-speeds of less than one-thousandth of an inch per second. According to the scientists who are developing this system, such fine measures of velocity are of prime importance in space missions. In a rendezvous(对接) between two spaceships, or in a landing approach by a vehicle onto an orbiting space station, a bump could rip open a ship’s skin, or a nudge could knock the station out of its orbit.
The light-beam radar, which operates at a frequency of trillions of cycles(百万兆) per second, could easily detect and measure the movement of a vehicle edging up to a satellite space station. A control system using so precise a signal as this would allow a huge vehicle to dock at a space station as lightly as a feather.
选项
A、measures the movement of a spaceship by means of light beam
B、makes use of microwaves
C、makes use of sound waves
D、both A and B
答案
A
解析
根据第一段第二句:a new system of radar that makes use of a beam of light...
转载请注明原文地址:https://kaotiyun.com/show/nJAd777K
本试题收录于:
公共英语二级笔试题库公共英语(PETS)分类
0
公共英语二级笔试
公共英语(PETS)
相关试题推荐
Mrs.SuePearson:Wedon’twanttobehere,butwhatcanwedo?Yousee,lastyearmyhusbandfoundoutthathehadcancer.
Ingeneral,Americanfoodismildtasting:mostAmericansdonotseasontheirfoodtoanygreatdegree.Saladsareverypopular
Ourcountryhasbecomeasocietyofemployees.AhundredyearsorsoagoonlyoneoutofeveryfiveAmericansatworkwasemploy
FollowingMartinWedell’spiece"Localteacherornativespeaker?"nowisperhapsagoodtimetoexplorethediscomfortoverthe
ThereisacommonresponsetoAmericaamongforeignwriters:TheUSisalandofextremeswherethebestofthingsarejustase
Technologyhasbeenanencouragementofhistoricalchange.ItactedassuchaforceinEnglandbeginningintheeighteenthcentu
EveryyearformorethanadecadeI’vegonewithsomegoodmalefriendstothemusicfestival.Womenarenotinvited,buttheyd
Whoisthemanworkingwith?
LuciaAmour:Theinternetisapositiveinfluenceonmodern-daygenerations,keepingtheminformedonbothlocalandglobal
Thereasonwhymanyproductionprocessesweretakenoverbythemarketplacewasthat______.Itcanbeseenfromthepassageth
随机试题
处理僵局时的让步,首要的是防止让步失误,为此应注意哪些问题?
衡量生产力水平的客观尺度是()
婴儿期预防接种疫苗正确的是
下列哪项不是猩红热皮疹的特点
2000年5月县土地局向乙颁发国有土地使用权证的行为属于( )。如果2002年5月市土地局撤销了县土地局发给乙的国有土地使用权证,则乙( )。
甲研究所与刘某签订了一份技术开发合同,约定由刘某为甲研究所开发一套软件。3个月后,刘某按约定交付了技术成果,甲研究所未按约定支付报酬。由于没有约定技术成果的归属,双方发生争执。下列哪些选项是正确的?
记账凭证的填制是由( )进行的。
签订物业服务合同应注意()。
心理学家认为许多人在冬季比在夏季更易于受心理问题影响,并称这种现象为季节性情感紊乱。他们这一结论是以被调查者按要求对过去不同时期感受的回忆的调查结果为基础的。但是,有关人们是否都能清楚准确地回忆起他们过去的心理状态这一点是不清楚的。所以,调查结果并不能证明
下列选项中,属于政治上层建筑的有()
最新回复
(
0
)