根据本文，作者强调北宋选开封为首都主要因为当时该地：

试卷相关题目

SQL Error: select id,body,options from ***_enewstiku where sourceid='29365' and id < 2391812 and id<>'2391812' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku where sourceid='29365' and id > 2391812 and id<>'2391812' order by id asc limit 5