Here are the completed sentences with the appropriate forms of the words provided:

1. Yesterday a little child got **lost** and then a policeman helped him to find out the way home.
2. This charity organization is popular **with** citizens.
3. They have a **co-educational** program for young girls and boys.
4. The Y & Y helps to encourage young children to participate in a **recreational** program.
5. We should save our **natural** resources by reusing and recycling the used things.
6. She is **enrolled** for the activities for her summer vacation.
7. Please fill in the **application** form with your personal information.
8. We should help the **handicapped** children with their homework.
9. BSA is a youth **organization**.
10. We should take care of our **health** and personal fitness.

(Note: Some words required minor transformations for appropriate use.)