题目

下列除去物质中所含杂质(括号内的物质)的方法不正确的是 ACO2(HCl)：通过NaOH溶液后用浓硫酸干燥 BN2(O2)：将气体缓缓通过灼热的铜网 CMnO2(KC1)：加足量水溶解，过滤，洗涤，干燥 DKNO3溶液(KCl)：加适量的AgNO3溶液，过滤 A．A                          B．B                           C．C                           D．D It will cost a lot of time．________, I think we shall need it and it will certainly be useful to us ________． [　　] A． What’s more; sooner or later B． As a result; now and then C． At the same time; more or less D． After all; here and there