单项选择题 In the （） refrigeration compressor one end of the crank shaft extends through the crankcase house for connection, via a coupling or pulley, to an external drive motor.

单项选择题 Which of the following will be desirable properties of refrigerant?（） (1) non-explosive (2) non-corrosive (3) that it doesn’t react with lubricants

单项选择题 In practice, the refrigerant flow after the evaporator is designed to ensure that the vapor leaving the evaporator is slightly （）.