改变电源的频率可以改变电动机的转速。（   ）

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SQL Error: select id,body,options from ***_enewstiku_ where sourceid='69465' and id < 4499171 and id<>'4499171' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku_ where sourceid='69465' and id > 4499171 and id<>'4499171' order by id asc limit 5