单选题 The Smiths ______ their breakfast when the morning post came.
A. had B. has been having C. are having D. were having

【正确答案】 D
【答案解析】本题考查的是时态。由于从句时态为came，所以排除B、C。又因为强调邮件到的这个时间点，所以选D。本句的意思是：“当早晨的邮件到了的时候，史密斯一家正在吃早饭。”