题目

Now Tom with his classmates ________ football on the playground. A.play                          B.are playing                C.plays                         D.is playing 答案：D 解析: Tom是主语，with...是状语。下列有关溶液的说法中，正确的是A.溶液是由溶质和溶剂组成的B.稀溶液一定是不饱和溶液C.无色透明的液体一定是溶液D.溶液中只能含有一种溶质