填空题

请将如下程序补充完整,使得输出结果为:bbaa。
#include<iostream>
using naluespace std;
class A
public:
______eout<<"aa";

class B:public A
public:
~B( )eont<<"bb";

int ulain( )
B*P=new B;
delete P;
return 0;

【参考答案】

~A( )