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
专升本
Under proper conditions, sound waves will be reflected from a hillside or other such obstruction. Sound travels at the rate of a
Under proper conditions, sound waves will be reflected from a hillside or other such obstruction. Sound travels at the rate of a
admin
2010-10-31
97
问题
Under proper conditions, sound waves will be reflected from a hillside or other such obstruction. Sound travels at the rate of about one-fifth of a mile per second. If the hill is eleven hundred feet away, it takes two seconds for the sound to travel to the hill and back. Thus, by timing the interval between a sound and its reflection (the echo) , you can estimate the distance to an obstruction.
During World War II the British used a practical application of this principle to detect German planes on their way to bomb London long before the enemy was near the target.
They used radio waves instead of sound waves, since radio waves can penetrate fog and clouds.
The outnumbered Royal Air Force(RAF) always seemed to the puzzled Germans to by lying in wait at the right time and never to be surprised. It was radio echoes more than anything else that won the Battle of Britain.
Since the radio waves were used to tell the direction in which to send the RAF planes and the distance to send them (their rage of flight, in other words) , the device was called "radio directing and ranging" , and from the initials the word "radar" was coined.
It can be inferred from the passage that______.
选项
A、light waves could be used in a device similar to radar
B、radar was a practical application of a well-known principle
C、radar gready increased the effectiveness of the Royal Air Force
D、sound waves are reflected from a hillside under all conditions
答案
C
解析
雷达大大提高皇家空军的效率。第二段一句话“During World warⅡ…was near the target”和第三、四句话“The outnumbered Royal Air Force…won the Battle of Briton”都是围绕这个中心展开的。A项中的光波是错误的。B项中雷达是一个众所周知原理的应用。这个原理不是众所周知或常识性的,而是比较专业的。D选项中出现任何表示“绝对”意义的词汇,比如not at all,by no means,under no circumstance
转载请注明原文地址:https://kaotiyun.com/show/UgLC777K
本试题收录于:
英语题库普高专升本分类
0
英语
普高专升本
相关试题推荐
Hethoughtthatthebadworkingconditionswouldresultinthestrikeoftheworkers.
TomandJackhavereturnedbut______studentsofthegrouphaven’tcomebackyet.
You______meyourtelephonenumberincasesomeonewantstocontactyou.
Allgames______becauseoftherainstorm,manystudentscoulddonothingbutstudyintheclassroom.
Therearemanyproblemsinourmodernworld.Oneveryseriousproblemisenergy.Wegetagreat【71】ofenergyweneedfromcoal
LastnightafterdinnerItoldmyfamilythebadnews.1hadthisclassassignmenttomonitorouruseofenergyathomeforawe
Shehadclearlyno______ofdoinganywork,althoughshewasverywellpaid.
Thegovernment______topressurefromthetradeunionanddecidedtobettertheworkingconditions.
随机试题
A、Teachforeignlanguagesfortherestofhislife.B、Changewhathehasforhispastimaginaryworld.C、Exchangehistwo-story
使用VC++2010打开考生文件夹下blankl中的解决方案。此解决方案的项目中包含一个源程序文件blank1.c。在此程序中,函数fun()的功能是利用指针数组对形参ss所指字符串数组中的字符串按由长到短的顺序排列,并输出排序结果。ss所指字符串数组中有
财政统计的基本内容包括()
牙周袋深度是牙周组织破坏严重程度的标志,其超过5mm以上预后相对较差。
3个月患儿,消瘦,多汗,气短,因“肺炎”住院治疗。体检中发现有心脏杂音,经X线、超声心动图等检查诊断为“室间隔缺损”。此类心脏病易并发下列哪种疾病
下列属于职工薪酬范围的有()。
股东应当以其所拥有的选举票数为限进行投票,选举票数超过( )票的,应通过现场进行表决。
根据证券法律制度的规定,下列情形中,上市公司不得非公开发行股票的有()。
8类主要的性心理问题不包括()的类型。
______the1500’s______thefirstEuropeanexploredthecoastofCalifornia.
最新回复
(
0
)