首页
登录
职称英语
[originaltext] The idea of fighting a noise by making more noise sounds stra
[originaltext] The idea of fighting a noise by making more noise sounds stra
游客
2024-05-13
13
管理
问题
The idea of fighting a noise by making more noise sounds strange, but that’s exactly what motor engineers are doing in Germany and some other countries.
Carmakers’ research and development laboratories have already proved that mixing in more noise with the help of loudspeakers can reduce the unwanted noise.
Physicists have known about the technique for a long time. Sound is made up of pressure waves in the air. If two sound waves of the same frequency mix so that the highest point of one wave happens at the same time with the lowest point of the other wave, the result is no sound. Therefore, by producing a perfect copy of the noise and delaying it by half a wave cycle, we can kill the unwanted noise. Using this technique many carmakers are racing to develop noise-killing systems both inside and outside the cars.
Another good thing about the use of noise-killing systems is that it saves the need for a silencer, which not only reduces the weight of a car, but also makes the motor burn less oil and work better.
Some engineers believe that the noise-killing system will be used in most cars by 1996. But the carmakers haven’t decided if they will put it into production because it would add several hundred dollars to the cost of their cars.
Questions 29 to 31 are based on the passage you have just heard.
29. Which gives a general idea of how the noise-killing system works?
30. What can the noise-killing system do besides its main function?
31. Why isn’t the noise-killing system yet popular?
选项
A、It can make a car lighter.
B、It can make a car faster.
C、It can reduce the cost of a silencer.
D、It can improve the performance of a silencer.
答案
A
解析
选项中的It can make/reduce/improve等表明,本题可能考查It的作用。短文中提到噪音消除系统的优点之一:reduces the weight of a car。A)中的make a car lighter是对此的同义转述,故答案为A)。
转载请注明原文地址:https://tihaiku.com/zcyy/3596455.html
相关试题推荐
[originaltext]AndnowfortheMondayMorningweatherreport.Rightnowthe
[originaltext]AndnowfortheMondayMorningweatherreport.Rightnowthe
[originaltext]AndnowfortheMondayMorningweatherreport.Rightnowthe
[originaltext]AndnowfortheMondayMorningweatherreport.Rightnowthe
[originaltext]Thisweek,wetalkaboutgettinganAmericaneducationonli
[originaltext]RobertFrostwasborninSanFranciscoin1875andwassenta
[originaltext]M:Jenny,whatdoyouthinkamillionaireshouldbetike?W:Well
[originaltext]M:Jenny,whatdoyouthinkamillionaireshouldbetike?W:Well
[originaltext]M:Jenny,whatdoyouthinkamillionaireshouldbetike?W:Well
[originaltext]TheLibraryofCongress,thelargestlibraryintheUnitedSt
随机试题
FormorethanfivethousandyearsChinesedoctorshaveusedneedlestofight
Whatdoesthemanmean?[originaltext]W:Ihearthere’sagoodItalianrestauran
CrowdsourcingaBetterWorldThecrowdsourcingconcept—c
皮肌炎A.环形红斑 B.肢端硬性肿胀 C.上眼睑紫红色斑 D.下肢对称性出
根据《测绘成果质量监督抽查管理办法》,受检单位对监督检验结论有异议的,可提出书面
市场预测的首要任务是()。A.收集资料 B.选择预测方法 C.确定预测目标
公积金个人住房贷款具有的特点有( )。A.互助性 B.普遍性 C.利率高
基础心理学是研究()。 (A)正常成人心理现象的心理学基础学科 (B
根据《担保法》,抵押权自抵押合同生效时设立的是以( )为抵押合同。A.建设用地
总承包单位将其承揽的工程依法分包给专业承包单位。工程主体结构施工过程中发生了生产
最新回复
(
0
)