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; //A
void set(int i)x3=i; //B
;
void main()
B bb;
bb. a3=10 //C
bb. b3=10 //D