2块砖重5千克，400块砖重____千克，是____吨。

84 42 17 53 31 57 24 55 06 88 77 04 74 47 67 217633 50 25 83 92 12 06 76

63 01 63 78 59 16 95 55 67 19  98 10 50 71 75  12 8673 58 07 44 39 52 38 79

33 2112 34 29 78 64 56 07 82 52 42 07 44 38 15 5100 13 42 99 66 02 79 54

增加：在缺词处加一个漏字符号（∧），并在其下面写出该加的词。

删除：把多余的词用斜线（＼）划掉。

修改：在错的词下画一横线，并在该词下面写出修改后的词。

注意：1）每处错误及其修改均仅限一词。

2）只允许修改10处，多者（从第11处起）不计分。

    Today, I had a very had luck. I was fighting for fun with some classmates after physical education. I wave my arm with such great strong that my watch got loose and flew off my wrist! Just then, some girls were passing by and a flying watch hit one girl's mouth exactly, these two teeth were knocked off. My mother was called in to deal the matter. We made an apology to the girl but took her to hospital to treat my wound.

    I was teaching a great lesson in this incident. I shouldn't have been made sudden and strong actions. From now on, I'll take care to do anything, acting quiet and carefully!

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”）．