单项选择题
A.yellowish flame B.golden yellow flame C.white flame D.brilliant white flame
Black smoke coming from a boiler can be caused by （）.A....
单项选择题Black smoke coming from a boiler can be caused by （）.
A.low water level B.low oil pressure C.excessively high fuel pressure D.an improper air/fuel ratio
Which of the following pumps belongs to centrifugal pum...
单项选择题Which of the following pumps belongs to centrifugal pump?（）
A.Reciprocating pump B.Screw pump C.Diffuser pump D.Water-ring pump
The advantage of a centrifugal pump as compared with a ...
单项选择题The advantage of a centrifugal pump as compared with a reciprocating pump is that （）.
A.discharge is continuous B.it has no internal valves C.upon accidental closing of discharge valve, excessive pressure will not build up D.all of the above are true
