Answer:
What is black when it is clean and white when it is dirty?
What is the sun’s favorite day of the week?
If four people can repair four bicycles in four hours, how many bicycles can eight people repair in eight hours?
I weaken all men for hours each day. I show you strange visions while you are away. I take you by night, by day take you back. None suffer to have me, but do from my lack.
What never ends but you always have it
I am the same written forward backward and upside down.