单项选择题
A.liquid B.oily mixture C.emulsion D.vapor
Freon 12 which is used to produce intense cold is norma...
单项选择题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
The quantity of cooled air delivered by an air conditio...
单项选择题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
The shutter of the evaporator was blocked with （）, it m...
单项选择题The shutter of the evaporator was blocked with （）, it means there was too much evaporation.
A.ice B.wooden board C.iron plate D.cotton waste
