What Am I Riddles

Question: I'm the eyelid to your life and hide you when you're inside.
You can draw me and you can pull me, but you must leave to see my good side.

What am I?

Question: Half of those who read this riddle, I am your best friend.
I depend on you, but it's you I will defend.

What am I?

Question: What goes up and down the stairs without moving?

Question: There is an ancient invention still used in some parts of the world today that allows people to see through walls.What is it?

Question: What has four legs and can't walk?