单项选择题
A.must be provided B.may be provided C.have provided D.can be provided
In order to ensure perfect atomization, the fuel oil （）...
单项选择题In order to ensure perfect atomization, the fuel oil （） before injection.
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
