Answer:
What can be swallowed, But can also swallow you?
Who makes it, has no need of it. Who buys it, has no use for it. Who uses it can neither see nor feel it. What is it?
What flies forever, Rests never?
Black we are and much admired. Many seek us if they are tired. We tire the horse, and comfort man, and turn White when we've fulfilled your plan.
What I am filled, I can point the way. When I am empty. Nothing moves me. I have two skins. One without and one within.
What did the piece of wood say when he saw the screwdriver and screws approaching?
Difficult
Animal
Easy
Food
Funny
Kids
Logic
What am I?