单项选择题
A.0~05Mpa B.0~95Mpa C.1~05Mpa D.0~5Mpa
The crane jib is raised and lowered by means of （）A.a m...
单项选择题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
Which one of three elements for a fire on a tanker vess...
单项选择题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
Which system(s) in the hydraulic systems of crane alway...
单项选择题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
