单项选择题
Two main lubricating oil pumps are usual and are obligatory in （）.
A.container ships B.bulk carriers C.passenger ships D.barges
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.
单项选择题 In motorships，there are two main circuits, （）.
单项选择题 Auxiliary machinery covers everything onboard except （）.
