单项选择题
A.The alternators are not generating the same voltages and should be adjusted on automatic voltage regulator rheostats
B.Alternator frequencies are different and should be adjusted on the governor speed controllers
C.Alternators are out of phase and should be tripped and paralleled again
D.One alternator has lost one of its phases
单项选择题 Operational amplifiers, used primarily in analog circuits, are characterized by（）
单项选择题 CFC refrigerants exposed to high temperature or direct flame, will decompose and may produce（）
单项选择题 The major difference between the discharge and suction valves installed in most low pressure, reciprocating air compressors is that（）