题目

We enjoy _____ at home for vacation.                                                                             A. to relax              B. relaxing           C. relaxed              D. relaxes          答案：B比较等物质的量浓度的①H2SO3　　②NaHSO3　　③Na2SO3三种溶液中c()浓度的大小其排列的正确顺序是 [　　] A．①＞②＞③B．③＞②＞① C．②＞①＞③D．③＞①＞②