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單項選擇題

In the sentence “In some designs the cylinder oil is timed so that the oil injects only on the piston ring belt, the "piston ring belt" means （）.

A.piston crown
B.piston ring groove
C.piston skirt
D.piston ring area

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單項選擇題

In the four-stroke engine, it takes （） to make one power stroke.

A.one propulsion
B.two propulsions
C.two revolutions
D.one revolution

單項選擇題

In the event of the cylinder starting valve leakage （） would pass into the air pipes and ignite the oil deposited.

A.cooling water
B.vapor from the boiler
C.starting air
D.hot gases

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