单项选择题
A.vapor
B.liquid
C.solid
D.None of the above is tree
单项选择题 The saturation temperature of the refrigerant must be （） that required in the evaporator refrigerated space.
单项选择题 The function of （） in a refrigeration plant using Freon is to move moisture from all refrigeration system.
单项选择题 The boiling and condensation points of refrigerant mainly depend on the （） exerted upon it.