单选题The burning of the fuel adds more heat to the air charge, causing it to expand and force the engine piston to do work on the crankshaftWhat does “it” mean in this sentence?()Athe burningBthe fuelCthe air chargeDthe engine piston

单选题
The burning of the fuel adds more heat to the air charge, causing it to expand and force the engine piston to do work on the crankshaftWhat does “it” mean in this sentence?()
A

the burning

B

the fuel

C

the air charge

D

the engine piston


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