叠加能用来求多个独立电源共同作用时的（   ）。

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SQL Error: select id,body,options from ***_enewstiku_ where sourceid='68474' and id < 4421092 and id<>'4421092' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku_ where sourceid='68474' and id > 4421092 and id<>'4421092' order by id asc limit 5