Answer:
Poor people have it. Rich people need it. If you eat it you die. What is it?
You may enter, but you may not come in. I have space, but no room, I have keys, but open no lock. What am I?
What invention lets you look right through a wall?
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 am the thing that is used to make your weight. What am I?
No matter how little or how much you use me, you change me every month.