Cars consume half the oil in the U．S．, and cause about half the urban pollution and one fourth the greenhouse gases around the world．They consume a similar percentage 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（排放）of 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 the only practical option．

The other alternatives are attractive in theory but in practice are either impractical or offer only insignificant 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．, public transportation and carpooling（合伙用车）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 public transportation and dense（稠密的）populations, cars still make up 80 percent 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（内燃机）, 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）．

1．From the passage we know that the increased use of cars will________．

       A．consume half of the oil produced in the world

       B．have serious consequences for the well-being of all nations

       C．widen the gap between the developed and developing countries

       D．put a huge economic burden on residents of large cities

2．The U．S． has to deal with the problems arising from vehicle use because ________．

       A．most Americans are not willing to switch to public transportation systems

       B．the present level of oil prices is considered unacceptable

       C．other countries will protest its increasing greenhouse emissions

       D．it should take a lead in preserving natural resources

3．The use of natural gas can not reduce the pollution effectively as________．

       A．oil companies are producing less polluting types of gasoline

       B．the price of natural gas is not acceptable

       C．oil companies has made no progress in developing natural gas

       D．it can not be burned in all kinds of car engines

4．Which of the following is the best solution to the problems mentioned in the passage?

       A．The use of highly efficient car engines．B．A reduction of vehicle use in cities．

       C．The development of electric cars．       D．The use of less polluting fuels．