单项选择题
A.compressor
B.condenser
C.throttle valve
D.evaporator
单项选择题 Since heat will not flow freely from a body at a （） temperature to another at a （） temperature, it is necessary to expend mechanical work, heat, or electrical energy from an external source to achieve refrigeration.
单项选择题 In the process of （）, liquid changes into gas.
单项选择题 If the capacity of the refrigeration compressor is too large, the saturation temperature will （）.