— Why on earth didn’t you answer the door? — I’m terribly sorry but the telephone too.A

问题补充：

— Why on earth didn’t you answer the door?

— I’m terribly sorry, but the telephone , too.

A. is ringing

B. was ringing

C. rang

D. was about to ring

答案：

A. is ringing

(答案→)B. was ringing

C. rang

D. was about to ring

解析：句意：--你究竟为什么不开门？--我真的很抱歉，但是电话也在想。说明在第一个人敲门的同时，电话也再响，表示过去某一时间正在进行的动作，用过去进行时，故选B