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單項選擇題

The crane jib is raised and lowered by means of （）

A.a mooring winch
B.a hoisting winch
C.a slewing winch
D.a luffing winch

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單項選擇題

Which one of three elements for a fire on a tanker vessel is most difficult to eliminate (isolate)?（）

A.a combustible element, fuel
B.energy (resources for ignition) to start the combustion
C.oxygen to support the combustion
D.both A and C are correct

單項選擇題

Which system(s) in the hydraulic systems of crane always hold(s) single side of load?（）

A.hoisting system only
B.hoisting system and luffing system
C.hoisting system and slew and slewing system
D.slewing system only