Answer:
I tremble at each breath of air, and yet can heaviest burdens bear. What am I?
I am the key that is the hardest to turn
My flavors ranges from strawberry to toe.
I contain five little items of an everyday sort. You can find all five in a tennis court.
I love spinach.
No matter how little or how much you use me, you change me every month.
What am I?
Animal
Difficult
Easy
Food
Funny
Kids
Logic