题目内容：

根据下列句子及所给单词的首字母，用适当形式填空。（每空限填一词）

1.People should stop cutting down trees, or the e        will become worse.

2.My mother is cooking in the kitchen. I think she is a great c       .

3.There are h          of birds in the sky.

4.Mr. Wang looks s        . He is always strict with us.

5.My sister was not happy, because she l      her favorite toy yesterday.