题目

某溶液中存在Mg2＋、Ag＋、Ba2＋三种离子，现用NaOH、Na2CO3和NaCl三种溶液使它们转化为沉淀并分离出来．要求每次只加一种溶液，滤出一种沉淀，则所加溶液顺序正确的是 A．NaCl、NaOH、Na2CO3                   B．Na2CO3、NaCl、NaOH C． NaOH、NaCl、Na2CO3                  D．NaCl、Na2CO3、NaOH 答案：AListen and chose the best answer. (听录音，选择合适的答语共10分） （1）A. Sarah goes to school by bus.B. I go to school by bus. C.I usually go to school at 7:30. （2）A. You can go by the No.5 bus.B.I often go there on foot. C. We can go by the No.5 bus. （3）A. Yes, it’s very far.B. Yes, there is.C. Yes, I am. （4）A. I’m going at 9:00a.m. B. I’m going to buy a postcard C. I’m going to the shoe store at 9:00 a.m.（5）A. I’m going to Beijing.B. I’m going to eat good food. C. You’re going to Beijing.