题目

制作叶横切面临时装片时，下面哪一步是多余的(     ) A．在载玻片上滴清水 B．取材料 C．盖盖玻片 D．染色 答案：D Why not ______ your teacher for advice when you don’t know ______ the problems?A. ask; what to do with B. to ask; how to deal withC. ask; what to deal with D. to ask; how to do with