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() { Dd;}

A.constructA
B.constructA
C.constmctA
D.constmctA destructA constructA constmctA constructA destructA constructA constructA destructA destructA constructA destructA destmctA destmctA destructA destmctA destructA