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
Although recent years have seen substantial reductions in noxious pollutants from individual motor vehicles, the number of such
Although recent years have seen substantial reductions in noxious pollutants from individual motor vehicles, the number of such
admin
2010-01-15
91
问题
Although recent years have seen substantial reductions in noxious pollutants from individual motor vehicles, the number of such vehicles has been steadily increasing. Consequently, more than 100 cities in the U. S. still have levels of carbon monoxide, particulate matter, and ozone that exceed legally established limits. There is a growing realization that the only effective way to achieve further reduction in vehicle emissions — short of a massive shift away from the private automobile — is to replace conventional diesel fuel and gasoline with cleaner-burning fuel such as compressed natural gas, liquefied petroleum gas, ethanol, or methanol.
All of these alternatives are carbon-based fuels whose molecules are smaller and simpler than those of gasoline. These molecules burn more cleanly than gasoline, in part because they have fewer, if any, carbon-carbon bonds, and the hydrocarbons they do emit are less likely to generate ozone. The combustion of larger molecules, which have multiple carbon-carbon bonds, involves a more complex series of reactions. These reactions increase the probability of incomplete combustion and are more likely to release uncombusted and photochemically active hydrocarbon compounds into the atmosphere. On the other hand, alternative fuels do have drawbacks. Compressed natural gas would require that vehicles have a set of heavy fuel tanks — a serious liability in terms of performance and fuel efficiency — and liquefied petroleum gas faces fundamental limits on supply.
Ethanol and methanol, on the other hand, have important advantages over other carbon-based alternative fuels: they have a higher energy content per volume and would require minimal changes in the existing network for distributing motor fuel. Ethanol is commonly used as a gasoline supplement, but it is currently about twice as expensive as methanol, the low price of which is one of its attractive features. Methanol’s most attractive feature, however, is that it can reduce by about 90 percent the vehicle emissions that form ozone, the most serious urban air pollutant.
Like any alternative fuel, methanol has its critics. Yet much of the criticism is based on the use of "gasoline alone" vehicles that. do not incorporate even the simplest design improvements that are made possible with the use of methanol. It is true, for example, that a given volume of methanol provides only about one-half of the energy that gasoline and diesel fuel do: other things being equal, the fuel tank would have to be somewhat larger and heavier. However, since methanol-fueled vehicles could be designed to be much more efficient than "gasoline alone" vehicles fueled with methanol, they would need comparatively less fuel. Vehicles incorporating only the simplest of the engine improvements that makes methanol feasible would still contribute to an immediate lessening of urban air pollution.
The author would most probably regard the criticism of methanol as ______.
选项
A、inaccurate because it ignores consumer’s concerns
B、misguided because of its exclusively technological focus
C、flawed because of the assumption on which it is based
D、invalid because it reflects the personal bias of the critics
答案
C
解析
观点态度题。针对对甲醇的批评,作者说:不过对它的批评是基于使用那些无法为使用甲醇进行最简单的设计改进而只能用汽油的车辆之上的。这句话说明,这些批评仅针对只能用汽油的车辆,是片面的,因而是有缺陷的(flawed,有瑕疵的,有缺陷的)。
转载请注明原文地址:https://kaotiyun.com/show/2e6K777K
0
专业英语四级
相关试题推荐
(1)EducationisanimportantthemeinyouthathleticsintheUS.Youngkids,energetic,rambunctious,coopedupinclass,yearn
(1)ScientistssayChandraprovidesfirstevidencethattwomysteriescancoexistinonegalaxy.(2)Inaverybrightgalaxy4
(1)TheParis-basedInternationalEnergyAgency(IEA),initsannualforecast,saidanumberoffactors,includingthesoaringcos
(1)Americansmayhavebeendistractedbytworeportsremindingthemofawideninggapbetweentherichandpoor.(2)TheCent
(1)Americansmayhavebeendistractedbytworeportsremindingthemofawideninggapbetweentherichandpoor.(2)TheCent
(1)Oneoftheunresolved—andratherbitter—disputesinevolutionarybiologyisbetweenthecreepsandthejerks.Thecreeps(sod
PASSAGETWOWhatreasonsdoestheauthorgivetoexplainwhypeoplefeeldifferentwhenspeakingdifferentlanguages?
PassageThreeWhatisthispassagemainlyabout?
Whatdothespeakersmainlydiscuss?
Ican’tfindJennyeverywhere.Where______shebe?
随机试题
第二次世界大战后,日本检察机关的设置采用【】
A、educatorB、normalC、organicD、lordshipA
项目竣工验收分两个阶段进行:项目竣工报告和验收报告。其中项目竣工报告是由()编制的项目实施总结。
某市园林管理处为兴建一座园林景观,经招投标与甲建筑公司签订了工程施工合同。甲建筑公司具有相应的建筑施工资质,但该工程实际由乙工程施工队施工,乙施工队借用甲建筑公司的名义进行缔约。工程竣工后经验收合格,乙施工队要求某市园林管理处支付约定的报酬,园林管理处经咨
《汽车贷款管理办法》中规定并首次明确除中国公民以外,在中国境内居住1年以上(含1年)的港、澳、台居民以及外国人均可申请个人汽车贷款。()
知识产权的组成部分中,保护费用最高的是()。
与收益相关的政府补助应计入当期损益。()
按照能否转换成公司股票,债券可分为()。
WhichAmericanpresidentwasinvolvedinWatergateAffair?
南部某战区一个10人小分队里有6人是特种兵,某次突击任务需派出5人参战,若抽到3名或3名以上特种兵可成功完成突击任务,那么成功完成突击任务的概率有多大?
最新回复
(
0
)