Nowadays more and more families own private cars.Private cars,as the product of modem civilization,have been playing a vital role in people's daily activities.First,private cars are a convenient means of transportation.You can go wherever you like.Secondly,there is no doubt that private cars will have a great impact on the economic growth.The rapid car industry growth will contribute much to keeping the country's economy growing at a higher rate in the near futrue.But every coin has two sides.The development of the private cars will bring about a series of problems.For example,the polluted air given off by cars will do great harm to our health,too many private cars will lead to traffic jams and a great deal of energy will be wasted and so on.So I think we should take advantages of private cars and make them serve us better.Meantime we hope that satisfactory solutions to these negative problems will be found soon.