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.
