为了改善气体分布，气体的进口管一般做成（ ）结构。

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SQL Error: select id,body,options from ***_enewstiku where sourceid='24908' and id < 2125102 and id<>'2125102' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku where sourceid='24908' and id > 2125102 and id<>'2125102' order by id asc limit 5