单项选择题
A.pre-injection fuel oil treatment B.lube oil filtration C.lube oil purification D.piston cooling
Wristpin bearings are difficult to lubricate because of...
单项选择题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
Internal combustion engine crankcase vent outlets must ...
单项选择题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
The interior of some diesel engine saltwater heat excha...
单项选择题The interior of some diesel engine saltwater heat exchangers are protected from corrosion by the use of（）
A.aluminum plates B.lead cathodes C.copper baffle plates D.sacrificial zincs
