1. (2016·嘉兴) 用方框中所给单词的适当形式填空。每词仅用一次，每空一词。

among     jacket    discover     main     necessary

1. （1） It is to have a good diet to stay healthy.

3. （2） David bought his father a on Father's Day.

5. （3） Jiaxing is the most beautiful cities in Zhejiang Province.

7. （4） The book, New Exploring, is written for young students.

9. （5） Scientists are working to a better way to fight air pollution.