单项选择题
What is meant by the term“luffing the boom”of a crane（）．
A.Stopping the boom
B.Topping or lowering the boom
C.Moving the boom left or right
D.All of the above
点击查看答案&解析
相关考题
-
单项选择题
What does “evel-luffing” accomplish during crane operations（）.
A.It prevents the load from swinging when the boom level is adjusted
B.Less power is needed when topping the boom with a load on the hook
C.It maintains the height of the load above the deck
D.All of the above -
单项选择题
They（）loading at 1400 hours．
A.started
B.finished
C.completed
D.reported -
单项选择题
The net productivity per gang-hour can be improved through a decrease of（）.
A.Cranes/derricks
B.Crane/derrick cycles
C.Crane/derrick cycle time
D.Weight per package
