It was ______ hard work, but completing it gave me _____ deep sense of satisfaction.

A．the; 不填

B．the; a

C．不填；a

D．a; the

有以下程序
#include ＜iostream＞
using namespace std;
class Base

int a;
public:
Base(int x)a=x;
void show() cout＜＜a;
;
class Derived: public Base

int b;
public:
Derived(int i):Base(i+1),b(i)
void show() cout＜＜b;
;
int main()

Base b(5),*pb;
Derived d(1);
pb=&d;
pb-＞show();
return 0;

运行后的打印结果是______。