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
2024-03-12
16
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/3526309.html
相关试题推荐
Recentlythegovernmenthasissuedsomepreferentialpoliciestoencouragecolle
Inrecentyears,mostcompaniesareinclinedtohirethepeoplewithhighdiplom
Althoughrecentyearshaveseensubstantialreductionsinnoxiouspollutants
Althoughrecentyearshaveseensubstantialreductionsinnoxiouspollutants
Aidedbytherecentabilitytoanalyzesamplesofairtrappedinglaciers,s
Aidedbytherecentabilitytoanalyzesamplesofairtrappedinglaciers,s
Aidedbytherecentabilitytoanalyzesamplesofairtrappedinglaciers,s
Therecent,apparentlysuccessfulpredictionbymathematicalmodelsofanap
Therecent,apparentlysuccessfulpredictionbymathematicalmodelsofanap
Inrecentyears,publishers,directorsandTVproducershavetakenakeenin
随机试题
Honeybeepopulationsdeclinedby13.6%overthewinter,accordingtoasurve
某青年体检时,发现肝内有一个偏强回声结节,最可能的是A.海绵状血管瘤 B.肝细
以下关于土样的液塑限联合测定试验,说法中正确的有()。A.塑限联合测定法适
咬合病的临床表现不包括A.磨损 B.磨牙症 C.牙周组织创伤 D.牙髓炎
1929年,中国对美国的生丝出口量下降了80%,造成这一现象的直接原因是(
生产新药或者已有国家标准的药品的,须经国务院药品监督管理部门批准,并发给药品A:
A.宽大畸形的QRS波群提前出现,其前无P波 B.P波提前出现,P-R间期
建筑工程设计文件编制必须遵守的要求有( )。A.贯彻国家有关工程建设的政策和法
政府鼓励增加出口的主要措施是( )。A.提高外贸企业职工工资 B.增加出口补
下列各项中,影响应收账款周转率指标的有( )。 A.应收票据 B.应收账款
最新回复
(
0
)