15. --- Who are the teenagers gathering at the school gate?

--- Well, if you _____ know, they are all my visiting students.

A．need

B．must

C．may

D．Will

药物流产的禁忌证是

A．哺乳期妊娠者

B．生殖道畸形者

C．孕7周内的妇女

D．剖宫产不足半年者

E．已诊断或可疑异位妊娠者