红细胞成熟所必需的物质是（ ）。

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SQL Error: select id,body,options from ***_enewstiku where sourceid='31199' and id < 2507005 and id<>'2507005' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku where sourceid='31199' and id > 2507005 and id<>'2507005' order by id asc limit 5