设有二叉树如右图所示，则前序序列为（ ）。

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SQL Error: select id,body,options from ***_enewstiku where sourceid='28853' and id < 2351154 and id<>'2351154' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku where sourceid='28853' and id > 2351154 and id<>'2351154' order by id asc limit 5