题目

     a fire, hotel guests are asked to remain calm. A. As a result of  B. In the event of  C. By reason of  D. In the time of 答案：B向KNO3溶液中滴加少量浓盐酸，然后分成等量的三份，第一份滴入淀粉碘化钾溶液，溶液将变成______色；第二份加入小铜片，反应的离子方程式为_________________________；第三份滴加少量AgNO3溶液，将看到有____________生成。