（多选）对称三相电源是指三个（   ）的正弦电压源。

试卷相关题目

SQL Error: select id,body,options from ***_enewstiku_ where sourceid='69389' and id < 4493039 and id<>'4493039' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku_ where sourceid='69389' and id > 4493039 and id<>'4493039' order by id asc limit 5