单项选择题
A.motor overload would open
B.relief valve would open
C.pump would eventually overheat
D.motor would overheat
单项选择题 In order to accurately measure very low pressures, which of the instruments listed should be used?（）
单项选择题 Reduced capacity, accompanied by vibration and noise at the suction of a centrifugal pump is a result of （）.
单项选择题 The refrigerant leaves the evaporator of a refrigeration system as a low pressure （）.