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單項(xiàng)選擇題

In a diesel engine, blow-by is generally the result of worn（）

A.valve guides
B.oil control rings
C.valve seats
D.compression rings

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單項(xiàng)選擇題

For optimum results, centrifugal purification of heavy fuel oil should be accomplished with the fuel at the lowest practicable（）

A.throughput
B.additive percent
C.cetane number
D.TBN number

單項(xiàng)選擇題

Diesel engine piston ring blow-by is usually caused by excessive ring clearance at the ring（）

A.back
B.side
C.gap
D.bottom