Large pipes or down-comers are fitted between the steam drum and （） to ensure good natural circulation of water.

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

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

A.Only one pump should be used at any time
B.The ship speed should be reduced to 70% of the normal
C.Watch keeping of the steering gear should be increased
D.Limitations of the steering gear should be logged but the bridge need not be informed