Answer:
If I have it I don't share it. If I share it I don't have it. What is it?
What is full of holes but still holds water?
I am lighter than air, but a hundred people cannot lift me. Careful, I am fragile. What am I?
One pace to the north. Two paces to the east. Two paces to the south. Two paces to the west. One pace to the north.
I stand in one place yet fill the whole room. I can be filled with molten rock and come in every hue. What am I?
No matter how little or how much you use me, you change me every month.