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單項選擇題

The most common cause of lowering the crankcase lube oil flash point is （）.

A.more water contents
B.contamination with fuel oil
C.higher temperature
D.sufficient cooling of oil mist

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單項選擇題

The mechanical efficiency of an engine （） because losses occur in the form of friction.

A.is always less than 100%
B.is always more than 100%
C.is always equal to 90%
D.is always less than 90%

單項選擇題

The marine diesel engine is a type of diesel engine used on ships The （） of its operation is not very difficult to understand.

A.principle
B.principal
C.cause
D.case

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