The steam boiler is part of a closed loop steam, whereby, after the energy of the steam is used up and it becomes water again, （） is collected and returned back to the boiler for heating up again to steam.

Care must be taken to condition the （）in the boiler to ...

单项选择题Care must be taken to condition the （）in the boiler to prevent scaling, and corrosion, which can weaken the pressure vessel.

The power and torque capability of the steering system ...

单项选择题The power and torque capability of the steering system must be such that the rudder can be swung from （）one side to（）the other side with the ship at maximum speed.

Certain requirements must currently be met by a ship’s ...

单项选择题Certain requirements must currently be met by a ship’s steering system.There must be （）independent means of steering, although where two identical power units are provided, an auxiliary unit is not required.