编写程序模拟中国人、美国人是人、北京人是中国人。除主类外，程序中还有4个类：People、ChinaPeople、AmericanPeople和BeijingPeople类。-Simulation prepared Chinese people, the American people, Beijing is the Chinese people. In addition to the main class, program, there are four categories: People, ChinaPeople, AmericanPeople and BeijingPeople class.