Answer:
It keeps you on the ground and stops things from floating around. What is it?
What demands an answer, but asks no question?
Mountains will crumble and temples will fall, and no man can survive its endless call. What is it?
I occur twice in eternity. And I'm always within sight.
A standard dimension for sandwiches and rulers
What do you purposefully put lots of in and on your body, but run away from when you encounter it outside?