answer: #Person2# tells #Person1# America has no birth control and most people have one or two kids, while some people decide not to have any child.
documents: #Person1#: I noticed an article in the newspaper about the problem of rapid growth of cities in America. I was wondering,do you Americans carry out of birth control policy? Can Americans have as many children as they want?
  #Person2#: Yes, we can have as many as we want. But most people decide to have only one or two. And some people decide not to have any.
  #Person1#: Why do they decide not to have any? In the old days, we Chinese always wanted to have as many as possible. Some still do now.
  #Person2#: Some people prefer to devote all their energy to their work or to seek their own interests and travel. And others see so many problems in the world that they refused to bring children into such a difficult environment.
  #Person1#: It's understandable.