题目

Presenter: Welcome to our programme. Today we have invited Fread Wocson, a driving instructor of over 20 years experience to talk to us about   61  (learn) to drive. Well, Fread, do you think   62   is getting expensive to learn to drive these days? Fread: Well, it depends.   63   you come for a private instructor like me, it’s going to be a bit   64   expensive than going to a big school. The thing is, people have usually heard of the big school and trust them, so they’d rather spend more money on big schools. Well, I get customers through personal connections. Prese（题文）正确的实验操作对实验结果和人身安全非常重要。下列实验操作错误的是（ ）A. 熄灭酒精灯 B. 监控氧气流速C. 称量氢氧化钠固体 D. 稀释浓硫酸 C 【解析】试题分析：A、用灯帽盖灭，符合操作要求，正确；B、氧气不易溶于水，可通过观察气泡来确定氧气流速，操作正确；C、天平为左物右码，且氢氧化钠具有吸水性和腐蚀性需用玻璃器皿盛装后称量，操作错误；D、浓硫酸稀释时放出大量的热，因此将浓硫酸缓慢加入水中并不断搅拌，操作正确。