赤铜矿的主要成分是Cu₂O，辉铜矿的主要成分是Cu₂S，将赤铜矿与辉铜矿混合加热发生以下反应： Cu₂S+2Cu₂O==6Cu+SO₂↑，关于该反应的说法中，正确的是

甲、乙两位同学分别用小球做遗传定律模拟实验。甲同学每次分别从I、Ⅱ小桶中随机抓取一个小球并记录字母组合；乙同学每次分别从Ⅲ、Ⅳ小桶中随机抓取一个小球并记录字母组合。将抓取的小球分别放回原来小桶后再多次重复。分析下列叙述，不正确的是（     ）

The______is a piece of metal，plastic or bone with teeth，used for tidying and arranging the hair．    

选择合适操作或仪器的序号填空：

①滴管 ②加热 ③坩埚钳 ④试管 ⑤检查气密性

     All students need to have good study habits. When you have good study habits, you will learn things quickly and also remember them easily. Do you like to study in the living room? This is not a good place, because it is usually too noisy. You need to study in a quiet place, like your bedroom A quiet place will help you only to think about one thing. When you study, do not think about other things at the same time. Only think about your homework. If you do so, you will do your homework more quickly, and you will make fewer mistakes.
    Good study habits are very important. If you do not have them, try to learn them. If your studyhabitsare already good. Try to make them better.