题目

已知实数满足，则的最小值，最大值分别为（    ） A．          B．          C．0,3            D．0,6 答案：B －Must I return the book this week? －No, you _________．You can _________ it for 20 days． [　　] A． mustn't：keep B． needn't; borrow C． needn't; keep D． mustn't; borrow