写出程序运行的结果 Public class Base Public virtual string Hello（) {return “Base”;} Pu

写出程序运行的结果

Public class Base

Public virtual string Hello() {return “Base”;}

Public class Sub:Base

Public override string Hello() {return “Sub”;}

1. Base b = new Base(); b.Hello;

2. Sub s = new Sub(); s.Hello;

3. Base b = new Sub (); b.Hello;

4. Sub s = new Base(); s.Hello;

请帮忙给出正确答案和分析，谢谢！