单项选择题

下面程序的结果是
#include<iostream.h>
class A
public:
A( ) cout<<"construtA"<<endl;
virtual~A( ) cout<<"destructA"<<endl;;
class B:public A

class C:public A

class D:public B,public C

void main( )
D d;

A.constructA
destructA
B.constructA
constructA
destructA
destructA
C.constructA
constructA
constructA
destructA
destructA
destructA
D.constructA
  onstructA
constructA
constructA
destructA
destructA
destructA
destructA