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單項(xiàng)選擇題

For an ordinary four-stroke engine the exhaust valves open （）.

A.after TDC
B.before TDC
C.after BDC
D.before BDC

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單項(xiàng)選擇題

For an ordinary four-stroke diesel engine the exhaust valves close （）.

A.after TDC
B.before TDC
C.after BDC
D.before BDC

單項(xiàng)選擇題

For a main diesel engine the lube oil in the bearings is drawn from （）, usually located in the bedplate.

A.a gravity tank
B.a sump
C.a vessel
D.a bottle

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