单项选择题

有如下程序: #include using namespace std; class Base{ public: virtual void Show(){cout<<’B’;} }; class Derived:public Base{ public: void Show(){cout<<’D’;} }; int main(){ Base *p1=new Derived; Derived *p2=new Derived; p1->Show(); p2->Show(); delete p1; delete p2; return 0; } 运行这个程序的输出结果是

A.BB
B.BD
C.DB
D.DD