单项选择题
What is/are the advantage（s）of cranes over conventional cargo booms（）.
A.Cranes are able to pick up and drop loads over a greater spotting area
B.Increased safety because the deck is clear of running and standing rigging
C.Simplicity of operation of the crane by its operator
D.All of the above
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相关考题
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单项选择题
What is the purpose of the equalizing beam aboard a crane vessel（）.
A.It allows for rotation of the hook in the single mode
B.It is required to“twin-up”30-ton pedestal cranes
C.It is used to pick up light loads
D.It is used to rigidly connect two cranes -
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 -
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
