根据句意及首字母或汉语提示，写出各句中所缺单词的正确形式。（每空一词，共10分）

小题1:As you go up a mountain, you have to overcome the earth’s g           which pulls you down.

小题2:The m             leaf has become the most important symbol of Canada since the national flag was introduced in 1965.

小题3:The little girl was t          at the thought of being left alone at home and cried.

小题4:He went to the United States in the 1980s and s                down there.

小题5:Don’t leave matches or cigarettes on the table w              reach of little children.

小题6:How quickly a fuel burns depends on how well it is mixed with              (氧气) or air.

小题7:The policemen were sent to find the black box because it showed why the plane had           

(坠毁).

小题8:The idea                 (存在) only in the minds of us young people today.

小题9:This problem is only                 (稍微) difficult so I can work out.

小题10:They claimed that when they were               (包围) by the gang they acted in self-defense.

根据《危险化学品安全管理条例》要求，安全使用许可证制度的适用范围包括（ ）。

A．使用危险化学品从事生产并且使用量达到规定数量的化工企业

B．使用危险化学品从事生产或者使用量达到规定的数量的化工企业

C．所有化工企业