Good Riddles

Question: What do you have that I use more than you do?

Question: Always old, sometimes new. Never sad, sometimes blue. Never empty, sometimes full. Never pushes, always pulls.

Question: How can you add 9 to become 6? (No subtracting).

Question: What can you touch but not see?

Question: Imagine that you're in a dark room where there is nothing except a drinking cup. There is a door out of the room but it is locked with 50 locks on the outside. There are guards pointing guns at the door so if you try to escape you will die. How do you get out of the room?