克拉霉素属于哪种结构类型的抗生素（）
A.大环内酯类
B.氨基糖苷类
C.β-内酰胺类
D.四环素类
E.氯霉素类
参考答案：A
― Are you free today?
― No. I have ______ work to do today than yesterday. [ ]
A. many
B. much
C. more
D. most
金融期权的购买者是以支付一定数量的期权费为代价拥有买卖选择权的.
