Answer:
I help engines spin and pants stay up
I am mother and father, but never give birth or nurse. I'm rarely still, but I never wander. What am I?
Mr. and Mrs. Mustard have five daughters and each daughter has one brother. How many people are there in the Mustard family?
I am needed for most animals and hardcover books
I open to close but I close to open. I'm surrounded by water but I'm never soaking. What am I?
Whoever made me don't want me. Whoever bought me don't need me. Whoever use me don't know me.