下面程序中错误之处是 ______。 #include＜iostream.h＞ class A{ private： int xl; protected:int x2; public:int x3; }; class B: public A{ private:int b1; protected:int b2; public:int b3; void disp(){cout＜＜x1＜＜b2＜＜end1;} //Avoid set(int i){x3=i;} //B }; void main() B bb; bb. a3=10 //C bb. b3=10 //D }