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單項選擇題

（） is sometimes used for piston cooling since leaks into the crankcase would not cause problems.

A.Diesel oil
B.Hydraulic oil
C.Lube oil
D.Mineral oil

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單項選擇題

（） fuel oils （） lubricating oils require treatment before passing to the engine.

A.Both；and
B.Neither；nor
C.Either；or
D.Both；or

單項選擇題

（） device is provided to prevent starting air from being admitted to the cylinder before the reversing is completed.

A.An automatic
B.A transmission
C.A self-regulating
D.An interlocking