Answer:
What two keys cannot open any door?
I help engines spin and pants stay up. What am I?
I am the key that is the hardest to turn
I am a pretty one, fluttering in the pale blue sky. Delicate, fragile on the wing, indeed I am a pretty thing. What am I?
Tear one off and scratch my head what was red is black instead. What is it?
It has no top or bottom, but it can hold flesh, bones, and blood all at the same time.