单项选择题
Impurities from the boiler water surface can be removed through the （）.
A.safety valve
B.blow down valve
C.scum valve
D.feed check valve
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相关考题
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单项选择题
You should frequently compare drum-mounted and remote-reading water level indicators（） between these have contributed to failures because of overheating through shortage of water, when a boiler was being oil-fired.
A.descriptions
B.discrepancies
C.different
D.deflections -
单项选择题
The safety valves should be tested and adjusted when the boiler survey is （）
A.completed
B.carried out
C.cleaned
D.steamed -
单项选择题
A donkey boiler is （）.
A.one to supply steam to the main propulsion turbine
B.an auxiliary boiler
C.A and B
D.neither A nor B
