第一心音的产生主要是由于（）

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SQL Error: select id,body,options from ***_enewstiku where sourceid='28666' and id < 2339603 and id<>'2339603' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku where sourceid='28666' and id > 2339603 and id<>'2339603' order by id asc limit 5