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單項選擇題

Air that may enter a refrigeration plant tends to collect in the （）.

A.upper part of the receiver
B.upper part of the condenser
C.down stream end of the cooling coil
D.outlet end of the condenser

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單項選擇題

Moisture should be kept out of an R-12 system because it tends to cause （）.

A.icing of the automatic controls
B.embrittlement of some parts of the automatic controls
C.sludge in the lubricating oil
D.all of the above

單項選擇題

Black smoke coming from a boiler can be caused by （）.

A.low water level
B.high water level
C.excessively high fuel pressure
D.low oil temperature

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