在下列程序的横线处填上适当的内容,使程序执行后的输出结果为ABCD。 #include<iostream> using namespace std; class A { public:A(){cout<<‘A’;} }; Class B: { public:B(){cout<<‘B’;} }; class C:virtual public A { public:C(){cout<<‘C’;} }; class D:public B,public D { public:D(){tout<<‘D’;} }; void main(){D obj;}
A.public A
B.private A
C.protected A
D.virtual public A