A.heightB.breadthC.depthD.lengthOur ship is more than 1……

单项选择题Our jumbo boom can（）20 tons.

A.lift
B.rise
C.elevate
D.hoist

单项选择题On which type davit does the davit head stay at the same height?（）

A.Radial
B.Sheath-screw
C.Quadrantal
D.Gravity

单项选择题On what type of pump would you find an impeller?（）

A.Centrifugal
B.Gear
C.Piston
D.Vane

单项选择题On navigational aids，what does the light characteristic Fl(2+1) mean?（）

A.A flashing light combined with a fixed light of greater brightness
B.Light flashes combined in groups，with a different number of flashes in each group
C.A light showing groups of two or more flashes at regular intervals
D.A fixed light varied at regular intervals by groups of two or more flashes of greater brightness

单项选择题On cargo booms，preventers are（）.

A.auxiliary guys
B.extra fair leads
C.steel bands
D.stops