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單項(xiàng)選擇題

（） 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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單項(xiàng)選擇題

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

單項(xiàng)選擇題

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