Answer:
The more you add the less it weighs. What is it?
I go around in circles, but always straight ahead, never complain, no matter where I am led.
I only exist when you are here. Where you never were I can never be.
If I drink, I die. If I eat, I am fine. What am I?
What kind of tree can you carry in your hand?
No matter how little or how much you use me, you change me every month.