Answer:
What is it that you must give before you can keep it
If you are unsure how to use one then just ask a flight attendant.
What can you hold in your left hand but not in your right hand?
How can the letters OWONDER be rearranged to make one word?
A person's greatest asset.
Though not a plant, has leaves. Though not a beast, has spine. Though many wouldn't need this thing, It's more valuable than wine.