题目

_______ many times , he still couldn’t understand it．        A．Told                 B．Having been told          C．He was told                 D．Though he had been told 答案：B 解析: 略3-甲基香豆素有香草味，可用于香料及化妆品，其结构简式为。关于它的说法正确的是A.分子式为C10H10O2B.分子中所有原子可能在同一平面上C.1 mol该有机物与Br2的CCl4溶液发生加成反应，可以消耗5 mol Br2D.1 mol该有机物与NaOH溶液反应，可以消耗2 mol NaOH