第28题: [单项选择]酯的醇解产物是() A. 醇和酸 B. 两种新醇 C. 两种新酸 D. 新醇和新酯 E. 醇和酰胺 参考答案:D 答案解析:酯的醇解反应是酯中的烷氧基被另一醇的烷氧基所置换的反应。
第29题: [单项选择]DCS的核心是()。 A. 操作员站 B. 现场控制站 C. 工程师站 D. 系统网络 参考答案:B
第30题: [单项选择]Hardly ______ the audience started applauding. A. had Prof. Smith finished his speech when B. Prof. Smith had finished his speech when C. had Prof. Smith finished his speech than D. Prof. Smith had finished his speech than 参考答案:A 答案解析:[解析] “no sooner...than...和hardly/scarcely...when...”结构,意为:“一……就……”在这样的句子中,当否定词no sooner,hardly,scarc