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
36
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 of the following could best replace the word "bounce" underlined in Paragraph 1?
选项
A、Overturn.
B、Groove.
C、Extend.
D、Rebound.
答案
D
解析
词义题型参见第95题注释,Then it receives the echoes produced when the waves bounce off objects. (……然后它(一个雷达装置)接收无线电波遇到物体后______的回声/波);既是回声/波,应是反弹回的;因此选项D“回弹”应为答案。
转载请注明原文地址:https://www.tihaiku.com/zcyy/3325088.html
相关试题推荐
Whyapersonhasnofriendships______somethingthatasurveycannotadequately
JordancannotpolitelymmdowntheinvitationtoanArabforeignministersconfe
Theimportanceofagriculturecannotbeoverstated.Morethan50percentof
Icannotthankyouvery.muchforyourkindness,Iowemysuccesstoyou.A、soB、
Apilotcannotflyaplanebysightalone.Inmanyconditions,suchasflyin
Apilotcannotflyaplanebysightalone.Inmanyconditions,suchasflyin
Apilotcannotflyaplanebysightalone.Inmanyconditions,suchasflyin
Apilotcannotflyaplanebysightalone.Inmanyconditions,suchasflyin
Apilotcannotflyaplanebysightalone.Inmanyconditions,suchasflyin
Apilotcannotflyaplanebysightalone.Inmanyconditions,suchasflyin
随机试题
Treesshouldonlybepruned(修剪,整枝)whenthereisagoodandclearreasonf
TheWelshnationalsymbolistheleekorthedaffodil,butthesymbolforScotla
America’smorecapitalistsportsfanscommonlyacknowledgethattheircountr
ThepurposeofthefirstsentenceinParagraphOneis______.[br]Theexample
拆船保险的保险标的主要是()。A.应拆的船舶或海上装置 B.已拆的船舶
1987年《中华人民共和国土地管理法》实施后,农村村民建房占用的宅基地,超过当地
矿渣水泥细度可以采用()指标表示。A.比表面积 B.0.075mm方孔筛
某孕妇,宫口开全1小时,阴道检查胎头矢状缝与骨盆横径一致,小囟门在3点,大囟门在
女,68岁。因腹主动脉瘤在某市级医院接受手术治疗,术中发生大出血,经抢救无效死亡
共用题干 某大型流通企业2011年年销售收入为1亿元,经过董事会商议,打算就2
最新回复
(
0
)