阅读下列短文，根据短文内容填空。在未给提示词的空白处仅填写 1 个适当的单词，在给出提示词的空白处用括号内所给词的正确形式填空。

In the past few years, the number of wild animals 【小题1】 (decrease). If nothing 【小题2】 (do), man will be punished by nature. 【小题3】 (lucky), people begin to take actions. Some nature reserves (保护区) 【小题4】 (build) now so that animals can live in peace. If everyone has the sense of protecting wildlife, it is certain that an atmosphere of wildlife protection will come into being.