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單項(xiàng)選擇題

For occasional heavy loads, two cranes can be arranged to work together. The operating （） for deck crane motors may be hydraulic electric.

A.principle
B.medium
C.instruction
D.voltage

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單項(xiàng)選擇題

In a general cargo crane, three principal movements are （）；（）；（）.

A.hoisting；luffing；slewing
B.lifting；raising；lowering
C.rotating；raising；handling
D.hosting；lowering；moving

單項(xiàng)選擇題

A warp end may be fitted for operating the derrick topping wire which adjusts the derrick （）.

A.length
B.slack
C.height
D.rotation direction

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