[单选题]The emulsion of the oil is mainly caused by ().A . the solid impurities of large particleB . the solid impurities of fine particleC . the water contentD . both water and solid impuritie
[单选题]Emulsion oils and sodium nitrite are both approved additives, but () cannot be used if any pipes are galvanized or if soldered joints exist.A . the latterB . latterC . formerD . the former
[单选题]E.mulsion oils and sodium nitrite are both approved additives, but the latter cannot be used if any pipes are or if ally soldered joints exit.A.chromedB.weldedC.galvanizedD.bolted