单选题 Cars account for half the oil consumed in the U. S. , about half the urban pollution and one fourth the greenhouse gases. They take a similar toll of resources in other industrial nations and in the cities of the developing world. As vehicle use continues to increase in the coming decade, the U.S. and other countries will have to deal with these issues or else face unacceptable economic, health-related and political costs. It is unlikely that oil prices will remain at their current low level or that other nations will accept a large and growing U.S. contribution to global climatic change.
Policymakers and industry have four options: reduce vehicle use, increase the efficiency and reduce the emissions of conventional gasoline-powered vehicles, switch to less harmful fuels, or find less polluting driving systems. The last of these--in particular the introduction of vehicles powered by electricity-is ultimately the only sustainable option. The other alternatives are attractive in theory but in practice are either impractical or offer only marginal improvements. For example, reduced vehicle use could solve traffic problems and a host of social and environmental problems, but evidence from around the world suggests that it is very difficult to make people give up their cars to any significant extent. In the U. S. , mass-transit ridership and carpooling have declined since World War Ⅱ. Even in Western Europe, with fuel prices averaging more than ＄ 1 a liter (about ＄ 4 a gallon) and with easily accessible mass transit and dense populations, cars still account for 80percent of all passenger travel.
Improved energy efficiency is also appealing, but automotive fuel economy has barely made any progress in 10 years. Alternative fuels such as natural gas, burned in internal-combustion engines, could be introduced at relatively low cost, but they would lead to only marginal reductions in pollution and greenhouse emissions (especially because oil companies are already spending billions of dollars every year to develop less polluting types of gasoline).

【正确答案】 B

【答案解析】要点归纳题。选项A、C和D均仅涉及问题的某个方面，只有B代表了私人轿车继续增长的真正后果。
[主旨大意]本文论述了私人轿车对环境带来的负面影响，分析了一些解决方案。
[名师点津]
1．greenhouse gases：意为“温室气体，能引起温室效应的气体”，如二氧化碳、甲烷等。
2．mass transit：意为“公共交通、公共运输”
3．carpool：意为“合伙使用汽车，拼车”，如：If a group of people carpool，they travel togethe to work，school etc．in one car and share the cost：拼车，是指几个人搭乘一部车去上班或上学，并且分担车资。