下列物质中，互为同系物的是  

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SQL Error: select id,body,options from ***_enewstiku_ where sourceid='20631' and id < 1810127 and id<>'1810127' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku_ where sourceid='20631' and id > 1810127 and id<>'1810127' order by id asc limit 5