单项选择题
A.Crescent B.Sheath-screw boom C.Quadrantal D.Radial
Static electricity may be built up by the（）.A.flow of p...
单项选择题Static electricity may be built up by the（）.
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
