It USES a mixture of petrol and air, and this mixture explodes and burns, to produce the energy which propels the car.
内燃机所用的燃料是汽油和空气的混合物。汽油夹着空气，燃烧后产生驱车动力。
2
The power stroke "uses up" the gas, so means must be provided to expel the burnt gas and recharge the cylinder with a fresh petrol-airmixture: this control of gas movement is the duty of the valves;