Answer:
What tree that definitely grows does not have a shadow and does not grow fruit?
Halo of water, tongue of wood. Skin of stone, long I've stood. My fingers short reach to the sky. Inside my heart men live and die.
They can be harbored, but few hold water. You can nurse them, but only by holding them against someone else. You can carry them, but not with your arms. You can bury them, but not in the earth.
Where do you go in through one hole and come out through two holes at the same time?
Almost everyone needs it, asks for it, gives it. But almost nobody takes it.
What did the piece of wood say when he saw the screwdriver and screws approaching?