求高手，以下程序运行结果以及具体过程？？？？？？
#include<iostream.h>class Base1
{
public:
Base1(){cout<<"class Base1"<<endl;}
};
class Base2
{
public:
Base2(){cout<<"class Base2"<<endl;}
};
class Level1:public Base2,virtual public Base1
{
public:
Level1(){cout<<"class Level1"<<endl;}
};
class Level2:public Base2,virtual public Base1
{
public:
Level2(){cout<<"class Level2"<<endl;}
};
class TopLevel:public Level1,virtual public Level2
{
public:
TopLevel(){cout<<"class TopLevel"<<endl;}
};
void main()
{
TopLevel obj;
}
