1. The people chose him.
He chose the people. He was the people's choice. He chose them.

2. Maria has a boyfriend.
He's Maria's boyfriend. She's his boyfriend. He's her girlfriend.

3. The game has ended.
It's the game. It's the end of the game. Ended it's game.

4. This school teaches music.
It's a music school. It's the school's music. It's the music's school.

5. Children play in this playground
The playground's children. It's playground's children. It's a children's playground.