单项选择题
A.winch B.crane C.derrick D.boom
Containers are loaded and discharged by （）(龙门吊).A. ship...
单项选择题Containers are loaded and discharged by （）(龙门吊).
A. ship’s derricks B. fork trucks C. gantry cranes D. shore cranes
Our heavy derrick has been （）(不用)for a long time.A. out...
单项选择题Our heavy derrick has been （）(不用)for a long time.
A. out of order B. out of date C. out of danger D. out of use
（）(调高) the derrick, please.A.HighB.TopC.AdjustD.Lower
单项选择题（）(调高) the derrick, please.
A.High B.Top C.Adjust D.Lower
