单项选择题
A.cargo crane B.jib C.safe working load D.oil pressure
When the union purchase derrick is operated, one derric...
单项选择题When the union purchase derrick is operated, one derrick is positioned over the quayside and the other almost vertically over the （）.
A.dock B.hold C.pedestal D.machinery space
In a general cargo crane, （） is fitted to lift the carg...
单项选择题In a general cargo crane, （） is fitted to lift the cargo load.
A.the slewing motor B.the luffing motor C.the hoisting motor D.none of the above
The crane is usually mounted on a pedestal to offer ade...
单项选择题The crane is usually mounted on a pedestal to offer adequate （） to the operator.
A.time B.space C.length D.visibility
