孕妇，33岁，孕36周，晨起突然发生持续性腹部疼痛伴 * * 少量流血。可能的原因是（）。

A.重度子痫前期致胎盘早剥

B.腹部外伤导致胎盘早剥

C.多次刮宫致子宫壁过薄

D.长时间仰卧位致胎盘早剥

E.长时间仰卧位致子宫破裂

— Why didn't you answer the phone?

— I'm terribly sorry,  but the doorbell________,  too.[ ]

A. is ringing  

B. rang

C. was ringing  

D. was about to ring