单项选择题
（） unit is mounted so as to raise and lower the cable from the spurling pipe, which is at the top and center of the chain or cable locker.
A.The cable lifter
B.The hoisting motor
C.The topping wire
D.The life-raft
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相关考题
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单项选择题
Topping wires fix the height of the derricks and （） to the deck may be used to prevent fore and aft movement.
A.stays
B.winches
C.barrels
D.brakes -
单项选择题
Large pipes or down-comers are fitted between the steam drum and （） to ensure good natural circulation of water.
A.fire-tubes
B.furnaces
C.water drums
D.water wall tubes -
单项选择题
With reference to a rotary vane steering gear system, which one of the following statements is true?（）
A.The three moving vanes and the three fixed vanes form three pressure chambers
B.The three moving vanes and the three fixed vanes form six pressure chambers
C.The three moving vanes and the three fixed vanes form nine pressure chambers
D.The three moving vanes and the three fixed vanes form twelve pressure chambers
