单项选择题

Water enters the rotating impeller through the entry, known as “（）”, at the centre.

A.eye
B.hole
C.balance holes
D.opening

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单项选择题

Which one is not the normal operation for boiler shutdown?（）

A.Carry out soot blowing if permissible
B.Change fuel supply to diesel oil
C.Close steam stop valves on boiler when pressure is reduced
D.Drain boiler empty when it has cooled down

单项选择题

The forced draught fan should be started and air passed through the furnace for several minutes to “（）” it of any exhaust gas or oil vapors.

A.blow
B.clean
C.scavenge
D.purge

单项选择题

A shallow dish positioned at the normal water level is connected to the（）This enables the blowing down or removal of scum and impurities from the water surface.

A.main stern stop valve
B.auxiliary steam stop valve
C.scum valve
D.blow down valve