单项选择题
Normally，potable water systems are connected directly to the（）.
A.fire-main system B.feed-water system C.freshwater sanitary system D.domestic water tank
单项选择题 Line throwing apparatus aboard ship must contain（）.
单项选择题 In order for the automatic lifeboat drain to operate properly（）.
单项选择题 In launching a covered lifeboat，what would safely lower the lifeboat from inside the lifeboat cabin?（）
