根据短文理解，完成下列各题。

    Helen and Linda are good friends. They are in the same class. They go to school five days a week. And they have seven classes a day. After school they play volleyball.

    The two girls' mothers are friends, too. They like sports. So they can play sports with the two girls on the weekend（在周末）. Linda's mother likes tennis and Helen's mother likes tennis, too. Can the two girls play tennis? Sure, they play it well.

    The four friends always play tennis in the morning, and watch TV in the afternoon. It's relaxing! The two girls like eating fruits. They like apples, strawberries and oranges. They think fruits are good and healthy. After playing tennis, their mothers always make (做) some fruit salad first. What good friends they are!

我国科学家屠呦呦因为“发现青蒿素（化学式为C₁₅H₂₂O₅）一种用于治疗疟疾的药物，挽救了全球特别是发展中国家的数百万人的生命”而获得2015年诺贝尔生理学或医学奖。磺胺（化学式为C₆H₈N₂O₂S）是青蒿素之前最热门的抗疟药物之一。回答下列问题：

实验室可用氯酸钾或过氧化氢制取氧气．

（1）过氧化氢的分解的变化可用下式表示：过氧化氢​水+氧气；上述变化所涉及的物质中，属于金属氧化物的是 ____，氧元素的化合价为﹣1价的是 ____．

（2）用氯酸钾或过氧化氢制取氧气的实验中，都需要加入少量二氧化锰，二氧化锰的作用是 ____；若未加入二氧化锰，则反应 ____（选填“不能发生”或“明显减慢”）．

计算：

（1）4﹣（﹣2）^﹣2﹣3²÷（﹣3）⁰；    

（2）（2a+b）（b﹣2a）﹣（a﹣3b）²．