Class Base1{

         …

         public:

             int a,b;

                           }

class Base2:public Base1{

             …

         public:

             int b,c:

       }

void f(){…

  Base2  d;

  d.a=1;

  d.b=2;//如果改成这样：d.base::b=2;就可以

  d.b=3;

  d.c=4;

  base *dp=&d;//也不行。

}