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單項(xiàng)選擇題

The rim of the piston may contain cut-out portions to accommodate （） when they open.

A.the gases
B.the air
C.the valves
D.the injectors

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單項(xiàng)選擇題

The removal of （） from lubricating oil will reduce engine wear and possible breakdowns.

A.contaminating water
B.contaminated additives
C.contaminated fuel
D.contaminating impurities

單項(xiàng)選擇題

The remaining oil in the lubricating pipes and ducts should be blown out with （）.

A.atmosphere
B.the fresh water
C.compressed air
D.chemical compounds