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
2025-02-02
12
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/3939649.html
相关试题推荐
Apilotcannotflyaplanebysightalone.Inmanyconditions,suchasflyin
Apilotcannotflyaplanebysightalone.Inmanyconditions,suchasflyin
Apilotcannotflyaplanebysightalone.Inmanyconditions,suchasflyin
Apilotcannotflyaplanebysightalone.Inmanyconditions,suchasflyin
Apilotcannotflyaplanebysightalone.Inmanyconditions,suchasflyin
Icannotthankyouverymuchforyourkindness,Iowemysuccesstoyou.A、soB、t
Howcanyoufightyourcancerifyoucannotlookit______theface.A、onB、byC、in
Icannotthankyouverymuchforyourkindness,Iowemysuccesstoyou.A、soB、t
Hecannotseeanythingwithouthisglasses,sohemadea______ofrememberingto
Somemedicalconditionscanoftencurethemselves______,withoutmedicalinterve
随机试题
Fortunatelytherearestillafewtastythingsforusgourmandstoenjoyinr
要解决问题,还需作系统而周密的调查研究,这就是分析的过程。(inorderto)Inordertosolvetheproblem,asyst
[originaltext]W:Mr.Smith,I’dliketotalktoyouaboutmytermpaper.Whenw
[originaltext]Millionsofdollarsarespenteveryyearinfightingtoothde
Therewasaheateddiscussionaboutcustomerserviceatthemeetinguntilthema
[originaltext]W:IheardyoujustgotbackfromaweekendtriptoSantaFe.Ih
某别墅住宅小区总20户(每户4人),最高日生活用水定额为250L/(人·d),每
某桥梁静载试验,裂缝、校验系数等测试结果正常,获取检算系数Z2后,代替Z1重新进
患者,女性,70岁。既往有高血压病史20年,胆囊炎病史10余年,2小时前感心窝部
近几年来,我国开始对国内20个制造业行业中820家企业的采购经理进行月度问卷调査
最新回复
(
0
)