单项选择题
Fuel is delivered into the combustion space by （）.
A.a cooling system B.a lubricating system C.an electric system D.an injection system
单项选择题 Fuel injection valves should be taken out, cleaned, and lifting checked every （）.
单项选择题 Fuel injection uses the jet pump system and a Woodward type hydraulic （） is used to control engine speed.
单项选择题 Fuel injected into a diesel engines cylinder is ignited by （）.
