下列函数中，最小正周期为 的偶函数为（    ）

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SQL Error: select id,body,options from ***_enewstiku_ where sourceid='16551' and id < 1390216 and id<>'1390216' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku_ where sourceid='16551' and id > 1390216 and id<>'1390216' order by id asc limit 5