Answer:
There are two sisters: one gives birth to the other and she, in turn, gives birth to the first. Who are the two sisters?
How can you throw a ball 20 meters, and have it come back to you without hitting anything?
What can you hold in your right hand but never in your left hand?
You draw a line. Without touching it, how do you make the line longer?
When does 4 - 1 = 5 ?
What did the piece of wood say when he saw the screwdriver and screws approaching?