用括号内所给单词的适当形式填空。
1. Have you ever _____ (meet) her?
2. What do you want _____ (do)?
3. Project Hope _____ (build) many schools all over China since 1989.
4. His little brother enjoys _____ (play) football after school.
5. It's easier _____ (learn) a foreign language when you visit a foreign country.