单项选择题
A.has to be cooled B.has heated C.has preheated D.has to be preheated
In large marine diesel engines cylinder oils usually co...
单项选择题In large marine diesel engines cylinder oils usually contain additives formulated to impart the （） to clean the rings and grooves.
A.inefficiency B.oiliness C.detergency D.purity
In general, （） is suitable for delivering small quantit...
单项选择题In general, （） is suitable for delivering small quantities at high pressure.
A.reciprocating pump B.gear pump C.centrifugal pump D.vane pump
In four strokes engine, the cycle of events is complete...
单项选择题In four strokes engine, the cycle of events is completed in four strokes of （）.
A.the cylinder B.the crankshaft C.the piston D.the cross-head
