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單項(xiàng)選擇題

Lubricating oil used in a diesel engine serves to（）

A.reduce the wear of bearing surfaces
B.cool the bearing surfaces
C.assist in sealing bearing surfaces
D.all of the above

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單項(xiàng)選擇題

Which of the terms listed below represents the operational speed at which excessive engine vibration is created?（）

A.Non-harmonic speed
B.Critical speed
C.Maximum speed
D.Design maximum speed

單項(xiàng)選擇題

A dirty fuel oil filter is can be detected by （）
Ⅰ.fuel oil analysis
Ⅱ.observing the pressure drop across the filter

A.Ⅰonly
B.Ⅱonly
C.eitherⅠorⅡ
D.neitherⅠnor

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