①为探究催化剂的种类对氯酸钾分解速度的影响，甲设计以下对比实验：

A．将3.0g KClO₃与1.0g MnO₂均匀混合加热

B．将x g KClO₃与1.0g CuO均匀混合加热

在相同温度下，比较两组实验产生O₂的快慢．B中x值应取____

A中反应的化学方程式是____

②乙探究了影响双氧水分解速度的某种因素．实验数据记录如下

本实验中，测量O₂体积的装置是图1中的____（填编号）．

实验结论：在相同条件下，____双氧水分解得越快．

丙用图2装置进行实验，通过比较____也能达到实验目的．

化简：$\sqrt{8}$﹣$\sqrt{2}$=____ .

    Fishermen and ____ (sail) sometimes claim to have seen monsters in the sea. ____ people have often laughed at stories told by seamen, it is now ____ (know) that many of these ‘monsters' which have at times been sighted are ____ (simple) strange fish. Occasionally, ____ (usual) creatures are washed to the shore, but they are rarely caught out at sea. Some time ago, however, a peculiar fish was caught near Madagascar. A small fishing boat ____ (carry) miles out to sea by the powerful fish as it pulled on the line. ____  (realize) that this was no ordinary fish, the fisherman made every effort not to damage ____ in any way. When it was eventually brought to shore, it was found to be over thirteen feet long. It had a head like a horse, big blue eyes, shinning silver skin and a bright red tail. The fish, which has since been sent to a museum ____ it is being examined by a scientist, is called an oarfish. Such creatures have rarely been seen ____ (live) by man as they live at a depth of six hundred feet.

下列句子中加横线的成语使用不恰当的一项是(            )。