根据句意及首字母或汉语提示完成单词。

1. There are so many things here that I can't  decide which one to c _____.

2. My English teacher often e _____ us to  study English hard.

3. Study hard, and you will make _____ (进步).

4. This is Ann's _____ (私人的) letter, please  give it to her.

5. Today is a _____ (特殊的) day in the history of our country.