正常肝实质组织平均声衰减系数为（dB/ cm . MHz)（     ）

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SQL Error: select id,body,options from ***_enewstiku where sourceid='25746' and id < 2163637 and id<>'2163637' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku where sourceid='25746' and id > 2163637 and id<>'2163637' order by id asc limit 5