单项选择题
In motor-ships, （）, after passing through main and motion bearings and oil cooled pistons, etcis either retained in the bedplate.
A.the fuel oil B.the lubricating oil C.the refrigerating oil D.the hydraulic oil
单项选择题 In motorships，there are two main circuits, （）.
单项选择题 Auxiliary machinery covers everything onboard except （）.
单项选择题 A （）, sometimes called filters, is a device designed to prevent the passage of unwanted solids into the system.
