题目

IV. 信息匹配（共5小题；每小题2分，满分10分） 首先, 请阅读下列的应用文: Here are some advertisements about English language training from newspapers. A. English Training Centre attached to Zhongshan University *Common English Course for primary school teachers during winter or summer vacations 3 weeks (500yuan); 4 weeks (700yuan). *Special course for those who are to take an examination for his/her promotion at lowest cost 800 yuan, 6 periods a day for a month. *English teachers training course: listening, speaking, reading and writing, 1 month at the cost 1500 yuan12．用如图所示装置测定空气中氧气的含量．请回答有关问题：（1）在集气瓶内加入少量水，将水面上面的空气分为5等份．（2）在燃烧匙内放入足量的红磷．（3）充分反应后，待冷却至室温，打开止水夹．（4）该实验得出的关于空气组成的结论是氧气约占空气总体积的五分之一．（5）下列做法会使实验结果产生明显误差的是AB．A．把红磷改为镁条  B．把红磷改为蜡烛  C．不打开瓶塞，用放大镜聚焦阳光点燃红磷．