You can play the guitar.（疑問）
Can you play the guitar?
You can dance.（疑問）
Can you dance?
I can sing well.(否定）
I can not sing well.
You can ski. （疑問）
Can you ski？
I like volleyball. (否定）
I don't like volleyball.
You play tennis.(疑問）
Do you play tennis?
You are a teacher. (疑問）
Are you a teacher?
I can make ramen.(否定）
I can not (can't ) make ramen.