Here are the full sentences based on the prompts given:

1. Pop music is more interesting than classical music.
2. Studying music is more interesting than studying maths.
3. People in the countryside are friendlier than people in the city.
4. Your writing is better than mine.
5. You have more free time than your sister.
6. She speaks English more clearly than me.
7. Peter is the most intelligent student in my class.
8. He is the most skillful player on the Vietnam team.
9. He plays most skillfully for the Vietnam team.
10. Gangnam Style is one of the most popular songs in the world.
11. Mozart is one of the most famous composers of classical music.
12. Puppetry is the most unique performance I have ever seen.
13. Peter is the most intelligent person I have ever known.