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
9
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] The word "shouts" underlined in Line 5 most probably means ______
选项
A、eavesdrops
B、yells
C、confesses
D、whispers
答案
B
解析
词义题型见本文第五行:雷达的基本原理就像一个人在洞穴中 时所发生的事的例子一样。声音遇到墙壁(岩壁)后的回声可以帮助他判定洞穴的大小。既然shouts会有回声,且可助人判断洞穴的大小,应是“喊叫、呼叫”之类的意思,因此选项B为答案。
转载请注明原文地址:https://tihaiku.com/zcyy/3939644.html
相关试题推荐
Icannotthankyouverymuchforyourkindness,Iowemysuccesstoyou.A、soB、t
Apilotcannotflyaplanebysightalone.Inmanyconditions,suchasflyin
Apilotcannotflyaplanebysightalone.Inmanyconditions,suchasflyin
Apilotcannotflyaplanebysightalone.Inmanyconditions,suchasflyin
Apilotcannotflyaplanebysightalone.Inmanyconditions,suchasflyin
Apilotcannotflyaplanebysightalone.Inmanyconditions,suchasflyin
Apilotcannotflyaplanebysightalone.Inmanyconditions,suchasflyin
Icannotthankyouverymuchforyourkindness,Iowemysuccesstoyou.A、soB、t
Thoughtheimitationjewelrycanfoolmanypeople,theycannot______uptoanexp
Hecannotseeanythingwithouthisglasses,sohemadea______ofrememberingto
随机试题
[img]2018m9s/ct_etoefz_etoeflistz_201808_0009[/img][br]Accordingtotheprofes
Accordingtothepassage,theaverageageofthefleetofDelta/Northwestis____
[originaltext]Didyouknowthatthere’sakindofbirdthatcansew?Thisb
既可能带来损失,也可能产生利益的风险是( )。A:投机风险 B:纯风险 C:
患者,男性,38岁高处坠落后3小时入院。查体:意识清楚,血压90/60mmHg,
在以家庭为单位的健康照顾中,家庭的功能不包括A.抚养和赡养 B.家庭教育 C
房地产开发项目,应当符合( )。A、建筑工程质量、安全标准 B、建筑工程
在我国,对所有交易会员进行结算的期货交易所有()。A.中国金融期货交易所
(2017年真题)老年人因血浆蛋白含量低用药后游离型药物浓度可能明显增加的药物是
运输结构优化的最终目标就是争取以最少的投入取得最大的效益,这里的效益包括()。A
最新回复
(
0
)