Answer:
I break down buildings, I crumble mountains but you can't see me. What am I?
I have roots that no one sees and I am taller than trees. Up, up I go, but never do I grow. What am I?
The person who makes me doesn't need me. The person who buys me doesn't use me. The person who uses me doesn't know it. What am I?
I take off my clothes when you put on your clothes. I put on my clothes when you take off your clothes. What am I?
What can fill a room but takes up no space?
No matter how little or how much you use me, you change me every month.