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單項(xiàng)選擇題

When the heat load begins to increase, the needle valve of an expansion valve will（）

A.move in an opening direction
B.move in a closing direction
C.either open or close
D.not move at all

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單項(xiàng)選擇題

One of the main purposes of refractories in a boiler furnace is to（）

A.help preheat the air for the furnaces
B.help preheat the feedwater
C.protect economizer from excessive heat
D.prevent excessive furnace heat losses

單項(xiàng)選擇題

What is the first thing you would check on taking over a watch?（）

A.the bilges
B.the periscope
C.the water level
D.the oil pressure

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