用所给词的适式填空。
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).