只有（   ）存在时，同步发电机才能实现能量转换。

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SQL Error: select id,body,options from ***_enewstiku_ where sourceid='69467' and id < 4499375 and id<>'4499375' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku_ where sourceid='69467' and id > 4499375 and id<>'4499375' order by id asc limit 5