用所給詞的適式填空。
1. September is the _____________ (nine) month of a year.
2. We celebrate Children's Day on June _____________ (one).
3. There are twelve _____________ (month) in a year.
4. December is the _____________ (twelve) month of the year.
5. February is the _____________ (two) month of the year.
6. The flag of the U. S. has _____________ (star) and _____________ (stripe).