首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
Scientists now tend to agree that the noise level for potential hearing loss begins at about 70 decibels. Some of them are very
Scientists now tend to agree that the noise level for potential hearing loss begins at about 70 decibels. Some of them are very
admin
2013-01-20
51
问题
Scientists now tend to agree that the noise level for potential hearing loss begins at about 70 decibels. Some of them are very concerned because normal daily life often exposes people to noise levels of about 70 decibels even inside their homes. Cities have always been noisy,but noise is now spreading to areas that were quiet just a few years ago.
Clearly,something must be done or noise will seriously and permanently maim the population. Fortunately, the knowledge and methods to control noise already exist. As a matter of fact,this is one instance where the knowledge of control methods exceeds the knowledge about the effects on human life and on the environment.
There are two common means for control. The first is reducing noise at its source,and the second is changing the sound path by distance or by shielding.
The second approach is being used more often today as people become more aware of the danger of noise. New building codes require better sound insulation in homes and apartments. More and more towns are passing zoning ordinances that try to segregate noisy factories or airports from residential areas. Sound-absorbent materials and construction designed to block sound paths are slowly coming into use in offices and homes. New highways are being built to redirect traffic noise up and away from nearby areas. Aircraft are increasingly being required to use reduced power flights around airports.
There are many examples of available noise control methods that are not being used. More flexible building codes would permit the use of quieter kinds of plumbing pipes. Sound-absorbing materials can reduce the noise of motors and engines. Power generators van be quieted with baffles,exhaust silencers, and sound absorbers. Truck tires can be made with quieter treads. In many cases,the cost of building quieter machines is the same or only slightly higher than that of the current noisy ones. Even though the new equipment may cost more initially,it can prove more profitable in the long run. The new jumbo jets,for example,are quieter than the older ones,yet they are more powerful and carry twice as many passengers. All of these methods are only partial measures as noisy levels continue to rise. Most specialists in the field agree that much of the solution must come from eliminating some of the noise at its source,therefore saving through prevention the large costs of hearing loss.
Jumbo jets are mentioned as examples of_____.
选项
A、efficient transportation with low levels of noise
B、vehicles that cause serious air pollution
C、scientific advances that do more harm than good
D、quieter and older vehicle
答案
A
解析
题目问:大型喷气式飞机是作为什么例子出现的?第五段最后一句“The new jumbo jets…they aremore powerful and carry twice as many passengers.”通过这句话可知,新式的大型喷气机效率更高,并且能够装载更多的旅客。据此判断,应选择A。
转载请注明原文地址:https://www.kaotiyun.com/show/fi2O777K
0
考博英语
相关试题推荐
"Theprojectgoalisforstudentstobuildcomplexandinterestingsentences,and_____,wholeparagraphs."Theteacherexplains.
Whenhelefthighschool,he____togotocollegeandstudyforadegree,ratherthangetajobstraightaway.
Futuristshaveidentifiedtwochangesthatseemtobecentraltocontemporarysociallife.First,theUnitedStatesisbeingres
Writeacompositionofabout200wordsonthefollowingtopic.RemembertowriteyourcompositiononAnswerSheetII.
Scientistsgenerallyholdthatlanguagehasbeensolonginusethatthelengthoftimewritingisknowntocoveris_____incomp
FranklinDelanoRooseveltwastheU.S.Presidentwhenmanybusinesseswere_____duringtheGreatDepression.
Hegavehisworktohisfriendto_____,becausehefoundithardtoseehisownmistakes.
Inthispart,youareaskedtowriteacompositiononthetitleof"EffectofChina’sEntryintoWTOonPh.DPrograminChina"
Tidesarecreatedmainlybythepullofthemoonontheearth.Themoon’spullcauseswaterintheoceanstobealittledeeper
Theboardofthecompanyhasdecidedto______itsoperationtoincludeallaspectsoftheclothingbusiness.
随机试题
Theschooltook______measurestoprotectthestudentssafety.
治疗支饮脾肾阳虚证宜选用()
恒定水位柱形滤水器如图6-34所示,已知直径d=1.0m,土样高度h=1.2m,渗透系数k=0.01cm/s,土样上部水深H=0.6m,渗流量Q为()L/s。
采用填埋法处理垃圾时,一般采用的防渗技术有()。
企业年初取得50000元贷款,5年期,半年利率2%,每半年末等额偿还一次,则每半年末应偿还()元。(PVA2%,10=8.9826)
假定某国2016年国民生产总值为20000亿美元,短期外债余额为250亿美元,当年未清偿外债余额为1650亿美元,当年货物服务出口总额为2100亿美元,则该国当年负债率为()。
与债务筹资相比,股权筹资方式的优点有()。
公文的成文时间是指它的印制时间。()
用人单位的法定代表人与劳动者协商签订劳动合同的行为是()。
关于无形资产的后续计量,下列说法中正确的是()。
最新回复
(
0
)