單項(xiàng)選擇題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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1.單項(xiàng)選擇題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

3.單項(xiàng)選擇題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

4.單項(xiàng)選擇題The（）enables water to be blow down or emptied from the boilerIt may be used when partially or completely emptying the boiler.

A.main stem stop valve
B.auxiliary steam stop valve
C.feed check or control valve
D.blow down valve

5.單項(xiàng)選擇題The（） is fitted in pair one is the main valve, the other the auxiliary or standby.

A.main stem stop valve
B.auxiliary steam stop valve
C.feed check or control valve
D.blow down valve