单项选择题
A.flow of petroleum through pipes B.spraying or splashing of petroleum C.settling of solids or water in petroleum D.All of the above
Permission is kindly requested（）the ballast water.A.pum...
单项选择题Permission is kindly requested（）the ballast water.
A.pump out B.to pump out C.pumping out D.be pumped out
On a ship，a door that is required to be marked KEEP CLO...
单项选择题On a ship，a door that is required to be marked KEEP CLOSED is designed to（）.
A.prevent the passage of flammable gases B.prevent the passage of poisonous vapors C.delay the spread of heat and flames D.maintain watertight integrity
Limit switches are used on which davits?（）A.Sheath-scre...
单项选择题Limit switches are used on which davits?（）
A.Sheath-screw davits B.Gravity davits C.Radial davits D.Quadrantal davits
