What's a big problem in Shenzhen today, do you think? Besides pollution, traffic is, of course. There are too many people, too many cars but too little space so the roads are always busy. You can almost see traffic jams everywhere. It is even worse when everyone is going to school or to work. What's more, cars need fuel  to move, so they let out a lot of dirty smoke and pollute the air. However, the government is trying many ways to solve the problem. We can see more roads and footbridges over the main streets. And the workers are making some roads wider. It is said every car will have a computer. The computer can study the latest traffic news. Then it will look over its own map for the best way to drive and they won't get into traffic jams. The roads are always busy because    _   .
there are too many people and cars but there is too little space there are too many buses, subways and too many taxis they are very narrow and dirty there are too many buildings and there is too little space