along with the economic growth, private cars have penetrated into a wealth of citizens' lives because of its convenience features. undoubtedly, the widespread use of cars promotes the social productivity and enhances the economic development. but we are supposed to weigh strengths and weaknesses of the popularity of cars. with the growing prevalence of vehicles, a host of problems have emerged.

　　in the first place , car emissions are having an immeasurable effect on the world's climate. solid scientific evidence can confirm this harm. second, because the car depends so heavily on fossil fuels, it is a major source of carbon dioxide that causes global warming. additionally, soaring ownership of cars puts tremendous pressure on the limited capacity of current transport system. there is a heavy urban traffic flow with frequent traffic jam. these harmful side effects of autos burden our society with unacceptable costs to human health, the environment, and our economy.

　　so we must reverse this rising trend and promote the mass transportation. our heavy reliance on private cars must be reduced.