股权式衍生工具的种类有（）。
A.股票期货
B.股票期权
C.股票指数期货
D.股票指数期权
参考答案：A, B, C, D
He __________ this kind of music. He says it always makes him sleep. [ ]
A. likes
B. dislikes
C. unlike
D. unlikes
甲、乙两金属块，已知甲、乙密度之比为2：5，体积之比为1：2，它们的质量之比为______．
