Answer:
I am the thing that is used to make your weight. What am I?
I go through a door but never go in, and never come out. What am I?
I am the beginning of the end and the end of time and space. I am essential to creation and I surround every place.
I am whole but incomplete. I have no eyes yet I see. You can see and see right through me. My largest part is one fourth of what I once was.
I save lives on the ground and in the air
Almost everyone needs it, asks for it, gives it. But almost nobody takes it.