学习利用虚函数实现动态多态性。对实验四、五的所有类（Thesis类除外）实现ToString函数，返回类名。设计一个函数GetType返回其中任何一个类的对象的类名（注意不允许重载GetTpye，也就是说GetType只能有一个定义-Learning using virtual functions to implement dynamic polymorphism. Experiment four, five (Thesis except) ToString function returns the name of the class. Design a function GetType return the any class name of a class of objects (note that does not allow overloading GetTpye That GetType only one definition