二维超声主要是通过下列哪种原理进行成 像的

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SQL Error: select id,body,options from ***_enewstiku where sourceid='31793' and id < 2541716 and id<>'2541716' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku where sourceid='31793' and id > 2541716 and id<>'2541716' order by id asc limit 5