單項(xiàng)選擇題

When comparing different fuels for different engines, the ignition quality of diesel fuel oils becomes a less critical consideration as （）

A.the amount of lube oil additives increase
B.piston speeds increase
C.injection pressure decrease
D.engine speeds decrease

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單項(xiàng)選擇題

To reduce the weight of the reciprocating parts, pistons of high-speed engines are made considerably shorterThis results in （）

A.less piston slap and quieter running
B.increased crankshaft bearing wear
C.slightly greater piston wear
D.decreased side pressures

單項(xiàng)選擇題

Which of the following statements concerning cylinder liner wear is true?（）

A.Liner wear is distributed equally between the upper and lower portions of the cylinder
B.Excessive liner wear causes wear between piston ring and groove
C.Excessive, but uniform liner wear will not cause wear between piston ring and groove
D.Liner wear is normally greatest in the middle of the cylinder