Answer:
I have a straight back and sharp teeth to cut objects.
If you've got me I'm everywhere. If you share me I'm nowhere. What am I?
I have two bodies joined together as one. When standing still I run and run.
I hide in a dark tunnel awaiting my time. I can only be released by pulling back. Once released I may do unstoppable damage.
I am a king who's good at measuring stuff. What am I?
The answer I give is yes, but what I mean is no. What was the question?