With the development of cities, problems of big cities become increasingly distinctness, such as traffic jam, the pollution of cities and increase pressure which people have to face.  
Living in a big city is a dream for many people especially the younger one. For example in China, according to a research, about 70% graduate students want to go big cities like Beijing, Shanghai and Shenzhen, and about half of them will stay there util they died. Convenience is the major reason for people who want stay in big cities however it also become the biggest problem. Traffic jam is a headache issue for every person who live in cities, government want to solve this problem so they provide many sort of traffic like subways and buses. But the problem is people invade more road when they build subways make the traffic become more crowded.
Pollution which caused by traffic, factories and other human activities is an other problem in big cities. Private cars become the most common thing in this country, air pollution came by. Factories let waste water going into rivers cause great amount of fishes died and people who drink this type of water get sick.
Communication barriers, a illness caused by big pressure, is a usual emotional reaction when people under big pressure for a very long time. Competition which in this society become more and more intense especially for the young people who just graduate from school. They do not have time and do not want talk to their friends or parents.
Government should develop small towns in order to decrease the gap between big cities. So people stay their home can get a quality of life too.