15. Not until father came in ______ to prepare my lessons.

A．I began

B．did I begin

C．I had begun

D．had I begun

以下程序的输出结果是 [10] 。
#include＜iostream. h＞
void main()
int *p;
p=new int;
*p=200;
cout＜＜*p;
delete p;