— How many students are there in the room?

— Twenty _____, I'm not sure. [ ]

A. or so

B. or rather

C. about

D. more than

输卵管间质部妊娠的特点有（）。

A.停经时间长

B.危险性比壶腹部妊娠小

C.破裂发生晚

D.比峡部妊娠多见

E.可转变为宫角妊娠