Whether using a centrifuge or a simple filter, oil cleaning and filtration will be the most effective when the oil is at a （）.

单项选择题Exhaust valve grooving and corrosion is caused by certain components of residual fuel oilThese components are sodium, sulfur, and （）.

A.vanadium
B.carbon
C.copper
D.ash

单项选择题Which of the following problems may occur if the opening pressure of a fuel injection nozzle is greater than specified by the engine manufacturer?（）

A.The amount of fuel injected will be increased
B.The start of injection will be retarded
C.The nozzle will permit fuel to dribble
D.The spray pattern will be distorted

单项选择题The required amount in the change of speed necessary before a governor will make a corrective movement is known as （）.

A.speed droop
B.sensitivity
C.stability
D.promptness

单项选择题Turbulence in a diesel engine cylinder is of major importance in providing （）.

A.proper fuel metering
B.complete fuel/air mixing
C.minimal fuel penetration
D.proper fuel timing

单项选择题For a given fuel, a change in the compression ratio will affect the ignition lag by which of the listed means?（）

A.An increase in compression ratio will increase the ignition lag
B.An increase in compression ratio will decrease the ignition lag
C.A decrease in compression ratio will decrease the ignition lag
D.A decrease in ignition lag will increase the compression ratio