首页
登录
职称英语
Although recent years have seen substantial reductions in noxious pollutants
Although recent years have seen substantial reductions in noxious pollutants
游客
2023-08-23
28
管理
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 United States still have levels of carbon monoxide, particulate matter, and ozone(generated by photochemical reactions with hydrocarbons from vehicle exhaust)that exceed legally established limits. There is a growing realization that the only effective way to achieve further reductions in vehicle emissions—short of a massive shift away from the private automobile—is to replace conventional diesel fuel and gasoline with cleaner-burning fuels 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 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 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 cost 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 clone" vehicles that do not incorporate even the simplest design improvements that are made possibly 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-fuelled vehicles could be designed to be much more efficient than "gasoline clone" vehicles fuelled with methanol, they would need comparatively less fuel. Vehicles incorporating only the simplest of the engine improvements that methanol makes feasible would still contribute to an immediate lessening of urban air pollution. [br] The author describes which of the following as the most appealing feature of methanol?
选项
A、It is substantially less expensive than ethanol.
B、It has a higher energy content than other alternative fuels.
C、Its use would make design improvements in individual vehicles feasible.
D、Its use would substantially reduce ozone levels.
答案
D
解析
细节题。根据methanol定位到第三段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.“然而,甲醇最吸引人的特点还在于它可以减少90%形成臭氧的废气,而臭氧又是城市中最严重的污染物。”甲醇最吸引人的特点是它可以大量减少臭氧含量,和选项D的表述一致。所以答案选D。
转载请注明原文地址:https://tihaiku.com/zcyy/2950851.html
相关试题推荐
AccordingtothemostrecentAmericanFreshmansurvey,conductedannuallyby
AccordingtothemostrecentAmericanFreshmansurvey,conductedannuallyby
AccordingtothemostrecentAmericanFreshmansurvey,conductedannuallyby
AccordingtothemostrecentAmericanFreshmansurvey,conductedannuallyby
Go(围棋)isanancientAsiangame.Inrecentyears,computerexperts,particula
Go(围棋)isanancientAsiangame.Inrecentyears,computerexperts,particula
Go(围棋)isanancientAsiangame.Inrecentyears,computerexperts,particula
[originaltext]M:DoctorWhite,[22]werecentlylearnedthatalargepieceofthe
[originaltext]M:DoctorWhite,[22]werecentlylearnedthatalargepieceofthe
[originaltext]Recentlyafive-yearstudywasconductedbytheCenterforCh
随机试题
MustthePoorGoHungryJustSotheRichCanDrive?Sportsstars
How"SecondBrain"InfluencesMoodandWell-Being[A]AsOlympian
关于线性定常系统的传递函数,不正确的表述是( )。A.零初始条件下,系统输出
疲劳分为肌肉疲劳和精神疲劳。下列措施中,不属于消除精神疲劳的是()。A.播放音
关于β系数的含义,下列说法中正确的有()。 Ⅰ.β系数绝对值越大,表明证券
拔毒化腐生肌药多含砷、汞、铅等元素,多具剧烈毒性或强大刺激性,使用方法中错误的是
洞口作业的安全防范措施中,电梯井口必须设防护栏杆或固定栅门;电梯井内应每隔两层并
共用题干 患儿,女,5岁,发热伴右耳下疼痛2天,腹痛半天,入院查体:体温39.
某外国公司实际管理机构不在中国境内,也未在中国设立机构场所,2017年从中国境内
自美军在越战中大量使用脱叶剂(橙剂)造成二噁英污染,到1999年比利时等国发生"
最新回复
(
0
)