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單項(xiàng)選擇題

To counteract these undesirable effects cylinder oils usually contain additives formulated to impart a high degree of （） and detergency.

A.salinity
B.alkalinity
C.acid
D.sanitary

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單項(xiàng)選擇題

To avoid scavenge fires occurring the engine timing and equipment maintenance （）.

A.should be correctly carried out
B.should correctly be taken place
C.should carded with care
D.must to carry out with great care

單項(xiàng)選擇題

To avoid scavenge fires （） the engine timing and equipment maintenance should be correctly carried out.

A.occurred
B.occurring
C.not happening
D.occur

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