Good Riddles

Question: I am very strong and tough but can be broken in some ways. What am I?

Question: The more it dries, the wetter it becomes.

What is it?

Question: When you fall in me your as happy as could be, but you fall into depression when you lose me.

What am I?

Question: Suppose you're on a game show, and you're given the choice of three doors: Behind one door is a sports car; behind all of the others is bicycles. You pick a door, say No. 1, and the host, who knows what's behind the doors, opens another door, say No. 2, revealing a bicycle. He then says to you, "Do you want to pick door No. 3?" Is it to your advantage to switch your choice?

Question: Why don't most buildings have a 13th floor?