单项选择题
A.at the beginning of every watch B.at the beginning of the first watch every day C.at the completion of every watch D.at noon every day
According to the principle of two stroke diesel engine,...
单项选择题According to the principle of two stroke diesel engine, what is the number of its efficient work stroke per revolution?（）
A.1/2 B.1 C.2 D.3
Which of the following pumps will most affect oily wate...
单项选择题Which of the following pumps will most affect oily water separator performance and give the worst result?（）
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
