题目

You ____be tired—you have worked only for ten minutes．        A．won't       B．mustn't     C．needn't          D．can't 答案：D 解析: 略洗涤做过银镜反应的试管可以选用的试剂是 (    )A．氨水B．碱溶液C．稀硝酸 D．酒精