Answer:
Neither bought nor sold but more valuable than gold. It is built but not by hand. What is it?
What is it that has four legs, one head, and a foot?
I'm tall in the morning and short in the noon. I disappear at night but I will be back soon.
Of these things - I have two. One for me - and one for you. And when you ask about the price, I simply smile and nod twice.
Round as an apple, deep as a cup, and all the kings' horses can't fill it up. What is it?
When is it bad luck to see a black cat?