(+)
1. I can do it.
2. He can play the piano.
3. I can play the violin. My brother can play the violin too.
4. Kate can speak English.
5. She can speak Italian and Spanish.
(-)
1. I'm sorry, but I can't.
2. I can't sign.
3. They have lost their keys and can't come in the flat.
4. I can't do it.
5. I can't play the piano.
(?)
1. Can I help you?
2. Can I do something for you?
3. Can I have some coffee?
4. Can you do karate?
5. Can you sing a song to me?