开关断开时产生电弧的起始原因包括(   )。

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SQL Error: select id,body,options from ***_enewstiku_ where sourceid='69520' and id < 4503927 and id<>'4503927' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku_ where sourceid='69520' and id > 4503927 and id<>'4503927' order by id asc limit 5