题型:问答题 简答题 I called Mary many times yesterday evening. But I couldn’t get through. Her brother _____ on the phone all the time.A.talkedB.had talkedC.has talkedD.was talking 查看答案
题型:问答题 简答题 鉴别下列各组物质,所用的试剂或方法错误的是( )A.CaCO3粉末、Na2CO3粉末(水)B.Na2CO3溶液、NaCl溶液(紫色石蕊试液)C.Na2CO3溶液、KCl溶液(焰色反应)D.NaOH溶液、NaCl溶液(稀盐酸) 查看答案