题目

Most cell phone companies design models especially for kids. But parents are usually the ones buying the phones. According to a July 2012 study, 56% of parents of children aged 8 to 12 have given their children a cell phone. According to a recent YouthBeat survey, 12 is the magic number. It is the most common age for kids to get their first cell phone. But 13% of children aged 6 to 10 already have one. The number goes up with age. Pro­cell phone people, including many parents, notice that cell phones help kids keep in touch with their friends and families. They believe that cell phone实验室用如图所示装置制取氧气，下列实验操作正确的是A．加热前，将集气瓶注满水，用玻璃片盖着倒立在盛水的水槽中B．先将导管口移入集气瓶，再开始加热C．收集O2后，将集气瓶移出水槽，然后盖上玻璃片D．停止加热时，先熄灭酒精灯，再移出导气管