先天性肥厚性幽门狭窄多见于（）

A.男性足月儿

B.女性足月儿

C.男性早产儿

D.女性早产儿

E.男女一样多见

Someone called me at midnight but hung up _____ I could answer it. [ ]

A. as

B. since

C. after

D. before