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 pilot cannot fly a plane by sight alone. In many conditions, such as flying at night and landing in dense fog, a pilot must us
A pilot cannot fly a plane by sight alone. In many conditions, such as flying at night and landing in dense fog, a pilot must us
admin
2011-01-13
51
问题
A pilot cannot fly a plane by sight alone. In many conditions, such as flying at night and landing in dense fog, a pilot must use radar, an alternative way of navigating. Since human eyes are not very good at determining speeds of approaching objects, radar can show a pilot how fast nearby planes are moving. The basic principle of radar is exemplified by what happens when one shouts in a cave. The echo of the sounds against the walls helps a person determine the size of the cave. With radar, however, the waves are radio waves instead of sound waves. Radio waves travel at the speed of light, about 300, 000 kilometers in one second. A radar set sends out a short burst of radio waves: Then it receives the echoes produced when the waves bounce off objects. By determining the time it takes for the echoes to return to the radar set, a trained technician can determine the distance between the radar set and other objects. The word "radar," in fact, gets its name from the term "radio detection and ranging." "Ranging" is the term for detection of the distance between an object and the radar set. Besides being of critical importance to pilots, radar is essential for air traffic control, tracking ships at sea, and for tracking weather systems and storms.
What is the main topic of this passage?
选项
A、The nature of radar.
B、Types of ranging.
C、Alternatives to radars.
D、History of radar.
答案
A
解析
主旨题型通读全文可见本文讲的是雷达的功用,工作原理,名字的来源等;因此选项A为答案。
转载请注明原文地址:https://kaotiyun.com/show/dy5O777K
本试题收录于:
CATTI三级笔译综合能力题库翻译专业资格(CATTI)分类
0
CATTI三级笔译综合能力
翻译专业资格(CATTI)
相关试题推荐
Scientistshavediscoveredthatforthelast160,000years,atleast,there hasbeenaconsistentrelationshipbetween
A、TodescribewayspestscandamageplantsB、ToexaminethelifecycleofcaterpillarsC、ToexplainhowcomplantsdevelopD、To
NarratorNowlistentoaconversationbetweentwostudents.
OrganicArchitectureOneofthemoststrikingpersonalitiesinthedevelopmentofearly-twentiethcenturyarchitecturewasF
OvercomingtheLanguageBarrierThediscoverythatlanguagecanbeabarriertocommunicationisquicklymadebyallwhotra
OvercomingtheLanguageBarrierThediscoverythatlanguagecanbeabarriertocommunicationisquicklymadebyallwhotra
EconomicsWhydothestudentssaythis:
Somepeopleprefertospendmostoftheirtimealone.Othersliketobewithfriendsmostofthetime.Doyouprefertospendyo
Agoodtranslatorisbydefinitionbilingual.Theoppositeisnot【C1】______tree,however.Abornandbredbilingualwillstilln
随机试题
在建立国际政治经济新秩序的长期斗争中,必须始终()
女性,45岁,3小时前车祸头部受伤,伤后立即昏迷,做CT后入院,入院检查中度昏迷,右瞳孔散大,光反射消失,左上下肢肌张力增高,病理征(+),左顶枕有直径4.0cm头皮下血肿,CT示右额颞部高密度新月影像。最重要治疗是()
结核病的组织坏死属于
房屋登记机构予以异议登记的,申请人在异议登记之日起()日内不起诉,异议登记失效。
主动轮动策略的优点有()。Ⅰ.容易理解,且符合自上而下的投资理念,适合机构投资者进行行业配置Ⅱ.减少了对行业基本面和公司信息的依赖Ⅲ.抗风险能力得到增强Ⅳ.依据货币供应增速M2进行轮动,使得策略具有较强的可操作性
长江公司于2017年1月1日签署了一份关于向黄河公司销售一台大型加工机械设备的买卖约定,该设备的销售总价为4800万元,采用分期收款方式分6期平均收取,合同签署日收取800万元,剩余款项分5期在每年12月31日平均收取。长江公司于2017年1月1日发出该
法制国家
HappyMarriage,HappyHeartHappilymarriedpeoplehavelowerbloodpressure【C1】______unhappilymarriedpeopleorsingles,a
Passage1
A、Theyinvitedhimtoaparty.B、Theyaskedhimtomakeaspeech.C、Theygaveaspecialdinnerforhim.D、Theyinvitedhiswife
最新回复
(
0
)