可发生界面发射时，两种不同材料的声阻抗是（     ）

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SQL Error: select id,body,options from ***_enewstiku where sourceid='25728' and id < 2162956 and id<>'2162956' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku where sourceid='25728' and id > 2162956 and id<>'2162956' order by id asc limit 5