Was it raining hard when you _____ this morning?
A. left
B. leaves
C. was leaving
D. would leave
His parents _______ the US for ten years.
A. have been
B. have gone to
C. have been to
D. have been in
Who _____ over there now?
A. singing
B. are sing
C. is singing
D. sing
本病患者治疗首选药物是
A. 阿司匹林
B. 硫唑嘌呤
C. 环磷酰胺
D. 泼尼松
E. 氯喹