第3题: [单项选择]听下面一段对话,回答第8至第10题。What’s the woman’s problem A. She missed the wake-up call. B. Her room telephone is out of order. C. She is unable to get her breakfast in time. 参考答案:C 答案解析:W: Can’t you do something about the service in this hotel, manager
M: I’m sorry madam. What’s the
第4题: [单项选择]标定氰化钾标准溶液时,指示滴定终点的指示剂为()。 A. 试银灵 B. 甲基橙 C. 酚酞 D. 铬黑T E. 钙试剂 参考答案:A 答案解析:用硝酸银(AgNO3)标准溶液标定氰化钾标准溶液,以试银灵作指示剂,氰离子与银离子产生银氰络合物,稍过量的银离子与试银灵反应,使溶液由黄色变橙红色,即为终点。