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單項(xiàng)選擇題

Shaker, circulation and spray are the three general methods used in（）

A.pre-injection fuel oil treatment
B.lube oil filtration
C.lube oil purification
D.piston cooling

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單項(xiàng)選擇題

Wristpin bearings are difficult to lubricate because of their oscillating motion and（）

A.their free-floating design
B.their relatively small size
C.the reciprocating motion of the piston
D.their position in the lubrication system

單項(xiàng)選擇題

Internal combustion engine crankcase vent outlets must be equipped with （）

A.hinged rain guards
B.corrosion resistant flame screens
C.dipsticks for measuring oil levels
D.crankcase ventilation fans

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