单项选择题
The boiling and condensation points of a refrigerant depend on the （） exerted upon it.
A.temperature B.pressure C.velocity D.heat
单项选择题 Faulty operation of any system is indicated by very definite （）.
单项选择题 The refrigerating agent can （） at low temperature in the evaporator.
单项选择题 Because the expansion valve is just （） way open, the refrigerant is under low pressure in the evaporator.
