单项选择题 Because the expansion valve is just （） way open, the refrigerant is under low pressure in the evaporator.

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

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