单项选择题
A.sliding bowl bottom B.gravity disc C.separating disc D.scum valve
The （）pump is usually used as the lubricating oil pump....
单项选择题The （）pump is usually used as the lubricating oil pump.
A.turbine B.screw C.vaneejector D.centrifugal
The reciprocating pump can’t draw water from a tank may...
单项选择题The reciprocating pump can’t draw water from a tank may be caused by （）.
A.leaky pipe B.opened inlet valve C.too much water in tank D.None of the above
（）sometimes called filter, is a device designed to prev...
单项选择题（）sometimes called filter, is a device designed to prevent the passage of unwanted solids into the system.
A.Steam trap B.Check valve C.Separator D.Strainer
