参考点也叫零电位点它是由（   ）的。

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SQL Error: select id,body,options from ***_enewstiku_ where sourceid='69471' and id < 4499898 and id<>'4499898' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku_ where sourceid='69471' and id > 4499898 and id<>'4499898' order by id asc limit 5