单项选择题
The lubricating oil is pumped from the drain tank, very often with （） in the suction line.
A.a filter B.a strainer C.a magnetic filter D.a fine strainer
单项选择题 The lube oil in the bearings is drawn from a （）, usually located in the bedplate.
单项选择题 The lowest ring of a piston is （）.
单项选择题 The lower end of each piston rod is reduced in diameter to fit a bore in （）.
