单项选择题
Deck cranes require（） time to prepare for working cargo than derricks.
A.less B.more C.many D.much
单项选择题 The duty of a deck winch is to lift and lower a load by means of a fixed rope on （）.
单项选择题 Most anchor handling equipment incorporates （） for mooring purposes.
单项选择题 A variable displacement system of hydraulic drives consists of （）.
