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
28
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/3325084.html
相关试题推荐
Theimportanceofagriculturecannotbeoverstated.Momthan50percentoft
Theimportanceofagriculturecannotbeoverstated.Morethan50percentof
JordancannotpolitelymmdowntheinvitationtoanArabforeignministersconfe
靠临时抱佛脚要想通过外语课是不可能的。Youcannotgetbyinaforeignlanguagecoursebycrammingat
Theimportanceofagriculturecannotbeoverstated.Morethan50percentof
Icannotthankyouverymuchforyourkindness,Iowemysuccesstoyou.A、soB、t
Apilotcannotflyaplanebysightalone.Inmanyconditions,suchasflyin
Apilotcannotflyaplanebysightalone.Inmanyconditions,suchasflyin
Apilotcannotflyaplanebysightalone.Inmanyconditions,suchasflyin
Apilotcannotflyaplanebysightalone.Inmanyconditions,suchasflyin
随机试题
Differentthingsusuallystandfordifferentfeelings.Red,forexample,is
ADespitethewonderfulactionandBwell-developedplot,Cthethree-hoursmoviec
秘书人员的知识结构具有一系列明显的特征,那么秘书人员合理的知识结构应具备以下哪些
事物发展的周期性体现了()A.事物发展的直线性与曲折性的统一 B.事物发展是一
某制冷量为2000kW的溴化锂吸收式冷水机组,热力系数为1.15,冷却水进出口温
中耳的主要功能是A.防声作用 B.声阻抗匹配作用 C.保持中耳内外压力平衡
下列不属于中国古代官学的有()A.西周国学 B.汉代太学 C.唐代国子学
银行从业人员由于不当使用或泄露客户信息和银行技术信息,给客户造成损失或侵害客户利
新课程给教师角色的定位是学习者、( )A.监督者 B.定向者 C.促进者
熟悉的人容易从人群中被识别出来,这反映了知觉的( )规律A.选择性 B.理解
最新回复
(
0
)