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
单项选择题 In a general cargo crane, （） is fitted to lift the cargo load.
单项选择题 The crane is usually mounted on a pedestal to offer adequate （） to the operator.
单项选择题 In a ordinary cargo crane, （） is fitted to rotate the crane.
