程序代码：

#include "stdafx.h"
#include <iostream>
using namespace std;

class CA
{
public:
    CA(){cout<<"This is the constructor of CA"<<endl;}
    ~CA(){cout<<"This is the destructor of CA"<<endl;}
};
class CB
{
    CA a;//只知道这里是类的组合
public:
    CB(){cout<<"This is the constructor of CB"<<endl;}
    ~CB(){cout<<"This is the constructor of CB"<<endl;}
};
void fun(int n)
{
    static CA a;//这里不清楚为啥定义静态
    CB b;
    cout<<"n="<<n<<endl;
}
void main()
{
    fun(10);
    fun(20);
    CA *A;//这里不明白
    CB *pb=new CB;//这里也是
    delete pb;
}