实验室用高锰酸钾制氧气大致分为下列几步：其正确操作顺序为
①组装、连接仪器；②给药品加热；③检查装置的气密性；④装入药品于试管中；⑤用排水法收集氧气；⑥从水中取出导管并熄灭酒精灯
A．①③④②⑤⑥
B．①②③④⑤⑥
C．①③②⑤④⑥
D．③④②⑤⑥①
答案：A
分析：实验室制取氧气的步骤为：1、检查装置的气密性，2、装入药品，3、把装完药品的试管固定在铁架台上，4、点燃酒精灯加热，5、用排水法收集，6、把导管从水槽中撤离，7、熄灭酒精灯；可用七个字表示，即查、装、定、点、收、离、熄．
解答：解：实验室用高锰酸钾制取氧气的步骤为：①组装、连接仪器③检查装置的气密性，④装入药品于试管中，②给药品加热，⑤用排水法收集氧气，⑥从水中取出导管并熄灭酒精灯．故正确顺序为①③④②⑤⑥．
故选A．
| 短文改错 此题要求改正所给短文中的错误.对标有题号的每一行作出判断。 每行只有一个错误,请按下列情况改正： 该行多一个词：把多余的词用斜线(\ )划掉,在该行右边横线上写出该词,并也用斜线划掉 该行缺一个词：在缺词处加一个漏字符号(^),在该行右边横线上写出该加的词 该行错一个词：在错的词下划一横线,在该行右边横线上写出改正后的词 | |
| Last summer I go to America and studied at a language 1.________ school. I had many wonderful experience, but I also 2.________ had a sad one. One day, the school held party, where I 3.________ invited to talk about Beijing. After that they asked me lots of 4.________ things about China. But I couldn't explain it in English 5.________ clearly. I felt sadly. I learnt a lesson from this experience. I 6.________ have already studied English for eight years, I can't use it 7.________ very good. I must work hard to improve my spoken English 8.________ so that I will not be able to communicate freely with foreigners. 9.________ I hope I can be a bridge between China and others countries 10.________ in the future. |