Answer:
When I live I cry if you don't kill me I'll die.
Alone I am 24th with a friend I am 20. Another friend and I am unclean.
I have cities with no people, forests with no trees, and oceans with no water. What am I?
I'm sometimes white and always wrong. I can break a heart and hurt the strong. I can build love and tear it down. I can make a smile, but more often bring a frown. What am I?
I am in the middle of water but am not an island.
No matter how little or how much you use me, you change me every month.