Answer:
Taking this from a baby is said to be quite easy.
A white field, and when it is plowed, its soil is black.
What is black when it is clean and white when it is dirty?
If four people can repair four bicycles in four hours, how many bicycles can eight people repair in eight hours?
What divides by uniting and by dividing?
What never gets any wetter no matter how hard it rains?