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單項(xiàng)選擇題

（）, iea steam cooler, may be filled in the boiler system to control the superheated steam temperature.

A.An economizer
B.An attemperator
C.A water dram
D.A down-comer tube

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單項(xiàng)選擇題

Upon the completion of required tests, a （） should be placed on each extinguisher, showing the date and the person who completed the tests.

A.cap
B.disc
C.tag
D.cover

單項(xiàng)選擇題

If you must enter a room or compartment to combat the fire, keep an escape path （）.

A.open
B.close
C.opens
D.closes

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