单项选择题
A.reciprocating pump B.vane pump C.screw pump D.centrifugal pump
Which of the following pumps is most suitable for an oi...
单项选择题Which of the following pumps is most suitable for an oily water separator?（）
A.reciprocating pump B.vane pump C.mono pump D.axial-flow pump
With reference to a two ram actuating mechanism, which ...
单项选择题With reference to a two ram actuating mechanism, which one of the following statement is false?（）
A.The rams work inside cylinders B.The cylinders have glands sealing their open ends C.The rams are connected to a cross-head D.The cross-head is mounted on the rudder stock
The DC excitation to the field of brushless synchronous...
单项选择题The DC excitation to the field of brushless synchronous is generally produced by （）
A.an exciter driven by the same shaft with the generator B.an exciter driven by external prime mover C.generator itself D.either A and B
