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

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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