采用封闭母线，可以达到（  ）等方面的目的。 

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SQL Error: select id,body,options from ***_enewstiku_ where sourceid='69485' and id < 4500683 and id<>'4500683' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku_ where sourceid='69485' and id > 4500683 and id<>'4500683' order by id asc limit 5