早产最常见的原因包括（）。
A.生殖道感染
B.胎膜早破
C.妊娠合并心脏病
D.绒毛膜羊膜炎
E.子宫过度膨胀
参考答案：B, D
---When did the young man save you?
---January 1st,2000, the first day of the new century,_______ I can never forget.
A．when
B．which
C．that
D．where
