鸦片膏中含有多种生物碱。对于毒品而言，最主要起依赖作用的成分是（）。
A、可待因
B、吗啡
C、罂粟碱
D、蒂巴因
参考答案：B
We have two rooms __________ , but I can't decide ________.[ ]
A. to live；to choose which one
B. lived；choose which one
C. to live in；which one to choose
D. live；which one
覆板
