用于幼儿学习，测试，操作简单 建立多边形基类，并派生出长方形等子类。根据需要建立类的成员函数和成员方法，其中包括图像的学习部分和考核部分-For early childhood learning, testing, operation simple polygonal base class and derive a subclass of the rectangle, etc.. According to the need to create the class member functio