我国工频电压的频率为(  )。

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SQL Error: select id,body,options from ***_enewstiku_ where sourceid='69511' and id < 4503241 and id<>'4503241' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku_ where sourceid='69511' and id > 4503241 and id<>'4503241' order by id asc limit 5