等成本曲线围绕它与横轴(代表X)的交点逆时针转动表明（ ）。

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SQL Error: select id,body,options from ***_enewstiku where sourceid='31437' and id < 2520147 and id<>'2520147' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku where sourceid='31437' and id > 2520147 and id<>'2520147' order by id asc limit 5