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單項選擇題

One end of a cylinder for a medium or high-speed diesel engine is sealed by the piston and rings, the other end is sealed by the （）

A.crankcase
B.cylinder head
C.valve cover
D.engine frame

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單項選擇題

Which of the diesel engine components listed increase air density and helps to improve engine operating efficiency?（）

A.Impeller
B.Compressor
C.After-cooler
D.Exhaust differ

單項選擇題

Lube oil in the fresh water cooling system of a diesel engine may result from a （）

A.camshaft seizure
B.lube oil pump failure
C.lube oil cooler failure
D.lube oil pump overflow