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
相关考题
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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 -
单项选择题
With reference to rules governing steering gear, which one of the following rules is incorrect? （）
A.It is required that all ships are provided with two independent steering gear systems that is one main and one auxiliary
B.The auxiliary gear could be power operated in passenger ships
C.The auxiliary gear must be of adequate strength and sufficient to steer a ship at navigable speed
D.All moving parts of the steering gear must be guarded against any possible damage
