灰铸铁中的碳是以（ ）形式存在的。

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SQL Error: select id,body,options from ***_enewstiku where sourceid='24891' and id < 2124426 and id<>'2124426' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku where sourceid='24891' and id > 2124426 and id<>'2124426' order by id asc limit 5