单项选择题
What is the speed of the crankshaft in a four-stroke/cycle engine when the camshaft is turning at 750 rpm?（）
A.375 RPM B.500 RPM C.750 RPM D.1500 RPM
单项选择题 An electric heater built into some smaller diesel engines is used to （）.
单项选择题 A SECONDARY function of a waste heat boiler is to （）.
单项选择题 Fuel injection systems meter fuel, atomize fuel, and （）.
