We were very busy yesterday. Otherwise we _____part in the discussion.

A．would take

B．did take

C．had taken

D．would have taken

先兆流产与难免流产的主要鉴别要点是：（）

A．出血时间长短

B．下腹痛的程度

C．宫口扩张与否

D．早孕反应是否存在

E．妊娠试验是否阳性