Traffic is becoming worse and worse in big cities. Heavy traffic has caused a lot of      to people’s life and work. For example, people have to get up      to go to work on time and come back very late when their work is     .

There are many causes (原因) for      problems, but the following may be the most important ones. One cause is the great increase (增长) in the         of private cars. Cars need more space but they      fewer people. When more and more cars appear, roads and streets become very     . It also causes air pollution. The other cause is that some people don’t care about traffic     . They cross the streets even when the traffic lights are still     . This may easily cause traffic accidents. But how can we      these problems? I think if we go out by bus or by bike more often, we’ll use cars less. It may be a helpful way.

利用多孔介质方法研究（），就是虚拟一个等效的（）来近视代替复杂的裂隙介质场。