题目

 下列溶液，按由小到大顺序排列的是     ①溶液                    ②溶液 ③溶液                 ④溶液 A. ①②④③         B. ②①④③         C. ③④①②         D. ④③②① 答案：BThere are about ________ students in their school. [　　] A．three thousands of B．three thousand C．three thousand of D．three thousands