In China, most people ride bikes to school,or to work,or to places where they want to go.So China is called "kingdom of bicycles".    But Americans are a people on the wheel.Wherever you go, you will see cars.There are so many cars that there is a traffic jam here and there.Now, more and more Americans would not consider it a healthy way of life.In fact, many Americans are strongly against the advancement of the wheel.We should encourage people to use less cars to save our environment and the energy. Everyone wants to reduce pollution.But the pollution problem is very serious.People drive cars and the waste gas from them causes air pollution.On the other hand, the need for energy increases every day, and some sources of energy are running out. Oil will last for no more than 40 years, while coal could last another 300 years.The way we're heading is towards a world where people are going to go cold and hungry.Now in China many rich men live away from downtown.On holidays they go to some big cities and places of interest.Most of them use their own cars.But China is a country with a population of over 1.3 billion.So, if you have enough money in the future,what will you do? The waste gas from cars causes  _  .
air pollution traffic jams waste of money energy problems