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單項(xiàng)選擇題

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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單項(xiàng)選擇題

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

單項(xiàng)選擇題

The safety valves should be tested and adjusted when the boiler survey is （）

A.completed
B.carried out
C.cleaned
D.steamed

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