单项选择题
A.increased pump speed
B.excessive pump discharge pressure
C.too low of a tilting box angle
D.low pump speed
单项选择题 Which of the problems listed represents the major difficulty encountered with thermal expansion valve operation?（）
单项选择题 Broken valve strips in an operating low pressure, air compressor will cause （）.
单项选择题 Which of the listed operating conditions would have the greatest effect on the volumetric efficiency of an operating reciprocating air compressor?（）