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單項選擇題

As the refrigerant passes through the valve orifice, its pressure is reduced and part of the refrigerant turns into （）.

A.liquid
B.oily mixture
C.emulsion
D.vapor

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單項選擇題

Freon 12 which is used to produce intense cold is normally a （） when at atmospheric pressure and temperature.

A.liquid
B.gas
C.solid
D.water only

單項選擇題

The quantity of cooled air delivered by an air conditioning unit should （） the sum of the quantity of air re-circulated to the unit and the quantity mechanically exhausted.

A.balance
B.not balance
C.be more than
D.be less than

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