单项选择题
What is a cofferdam（）.
A.Tube fitted to an ullage hole B.Area the product is loaded into C.Void or empty space separating two tanks D.Opening in the deck used for cleaning a tank
单项选择题 What can cause a lack of oxygen in a chain locker（）．
单项选择题 Tonnage openings must be closed by means of（）.
单项选择题 The Vessel’s cargo holds are properly fitted with（）in way of hatches.
