单项选择题
In a diesel engine, exhaust valves open before the intake ports are uncovered to （）
Ⅰ.reduce pumping losses
Ⅱ.reduce back pressure
A.Ⅰonly
B.Ⅱonly
C.bothⅠand Ⅱ
D.neitherⅠnor Ⅱ
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相关考题
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单项选择题
Which of the engine components listed increases air charge density and helps to improve engine operating efficiency?（）
A.Intake manifold
B.Water-cooled exhaust system
C.After-cooler
D.Exhaust diffuser -
单项选择题
A diesel engine will lose power if fuel injection occurs too early because the （）
A.fuel will not be properly atomized in the cylinder
B.ignition will be delayed due to low ignition temperature
C.maximum fuel expansion will occur on the compression stroke
D.fuel will ignite before top dead center -
单项选择题
The air supplied to the cylinders by a turbocharger is often reduced in volume by a/an （）
A.air compressor
B.diffuser
C.after-cooler
D.ventilator
