Answer:
What does a stone become when in the water?
What is yours but only used by others?
I am neither a guest nor a trespasser in this place. I belong that belongs to me. Where is it?
It's tough as nails, Or soft as snow. People use it for their rink, Some just put in their drink.
What has no hands but might knock on your door, and if it does you better open up?
When is it bad luck to see a black cat?