53.We _______ our breakfast when an old man came to the door.　　　　 A)just have had 　　　　 B)have just had 　　　　 C)just had 　　　　 D)had just had

熱心網友

選 D. 后面已經有用過去時， 吃飯是發生在過去的過去，所以用過去完成時。