①可燃冰属于____（填“纯净物”或“混合物”）

②已知某种甲烷水合物的化学式：CH₄·8H₂O，其中含有____种元素；

1mol CH₄·8H₂O中约含有____个碳原子（用科学记数法表示）。

③化学家在较低的温度和压力下，用甲烷等为原料制成金刚石薄膜，该变化属于____

（填“物理变化”和“化学变化”）

④甲烷（CH₄）中氢元素为+1价，碳元素为____价，甲烷充分燃烧的化学方程式为____

⑤从环境保护的角度考虑，下列燃料中最理想的是____。（填字母序号）

A．甲烷       B．煤         C．氢气        D．汽油

增加：在缺词处加一个漏字符号（∧），并在此符号下面写出该加的词。

删除：把多余的词用斜线（＼）划掉。

修改：在错的词下划一横线，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。

    When Joe left university,she got a good job in the bike factory.But after he had been worked there for some years,he decided to have a change,so he put a notice in several newspaper.It stated what experience he had and the kind of job he will like to have.One of the answers he received was about a man looking for a job,too.This man wrote to him,"Dear sir,when you get a new job,being kind enough to give my name or address to your present boss as I have beer trying to find a position like yours for a long time."After he read the letter,he sudden realized he had done was really foolish.