首页
登录
职称英语
A pilot cannot fly a plane by sight alone. In many conditions, such as flyin
A pilot cannot fly a plane by sight alone. In many conditions, such as flyin
游客
2024-01-01
27
管理
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. [br] Which type of waves does radar use?
选项
A、Sound.
B、Heat.
C、Radio.
D、Light.
答案
C
解析
细节题型根据文章介绍的雷达工作的基本原理,见文中第?行:With radar, however, the waves are radio waves instead of sound waves. (然而,雷达所使用的不是声波而是无线电波);因此选项C为答案。
转载请注明原文地址:https://tihaiku.com/zcyy/3325089.html
相关试题推荐
FossilformationsliketheBurgessShaleshowthatevolutioncannotalwaysb
Somepeopleprefertospendmostoftheirtimealone.Othersliketobewith
Somestudentsprefertostudyalone.Othersprefertostudywithagroupof
Whyapersonhasnofriendships______somethingthatasurveycannotadequately
Theimportanceofagriculturecannotbeoverstated.Momthan50percentoft
Theimportanceofagriculturecannotbeoverstated.Morethan50percentof
JordancannotpolitelymmdowntheinvitationtoanArabforeignministersconfe
靠临时抱佛脚要想通过外语课是不可能的。Youcannotgetbyinaforeignlanguagecoursebycrammingat
Apilotcannotflyaplanebysightalone.Inmanyconditions,suchasflyin
Apilotcannotflyaplanebysightalone.Inmanyconditions,suchasflyin
随机试题
MyfriendsandIenjoydoingmanyofthesamethings.Inthatrespect,wehavea
()定期贷款()逾期贷款[br]()风险评级制度()外地信贷O、I
RelationshipTalkingPoints:SpeakYourSpouse’sLanguageA)Anna
[originaltext]W:Whydon’tyoubeginbytellingsomethingaboutyourself?M:Wh
[originaltext]FormerChelseafirstteamdoctorEvaCarneirorejecteda1.2m
债券的一个基本特性是它的价格与它所要求的收益率呈反方向变动。()
HFA的策略包括( )A.人权 B.平等 C.自力更生 D.和谐 E.
短脉冲雷达测定路面厚度试验方法步骤中,将承载车停在起点后启动软件测试程序,令驾驶
输卵管妊娠最常见的病因,是A.输卵管发育或功能异常 B.慢性输卵管炎 C.输
患儿,8岁。因面部水肿、头痛、头晕就诊。尿液检查:蛋白(+),红细胞20个/HP
最新回复
(
0
)