The process of gaining or losing weight can be explained by comparing your body to your car.Both run (1) _____ fuel, food for your body and gasoline for your car.Both (2) _____ that fuel, first into heat, then energy, some of (3) _____ is used to do work, and some emitted as waste.And (4) _____ your car uses more energy when the engine is racing than when it is idling, (5) _____ does your body use more energy when you are working hard than (6) _____ you are resting.

　　For the purpose of this comparison, (7) _____, there is one significant difference between them.Your car cannot store fuel by turning it into (8) _____ else; all gasoline not (9) _____ remains as gasoline.But your body stores (10) _____ energy as fat.When the gas tank is completely empty, the car won’t run; but your body can burn fat to provide more energy.
____

A.in

B.on

C.for

D.against