A.100% B.75.6% C.50% D.25%
A.50Hz或25Hz B.30Hz或50Hz C.Hz或25Hz D.20Hz或25Hz
A.發(fā)電、輸電、變電、配電、用電 B.發(fā)電、輸電、配電、用電 C.發(fā)電、輸電、用電