Good Riddles

Question: What goes up but never go down?

Question: What do you get when you cross an elephant and a fish?

Question: Why was the woman fired from the car assembly line?

Question: You are a surgeon who has to perform 3 operations today, but you only have 2 pairs of gloves (a and b) to perform the operations. Each of the people you are performing surgery on are infectious so you cannot touch any of them or their bodily fluids and they can't touch each other's bodily fluids. How do you perform all 3 operations with only 2 pairs of gloves?

Question: What single line can you add to the following statement to make it true?

5+5+5=550