单项选择题
The component of a refrigerating system in which the refrigerant vaporizes and absorbs heat is known as the （）.
A.condenser B.vapor generator C.accumulator D.evaporator
单项选择题 The low pressure side of a refrigeration system is considered to exist from the （）.
单项选择题 If the electric motor driving an air compressor fails to start, the cause may be a （）.
单项选择题 The refrigerant gas returning to the compressor should be （）.
