需要一个阻抗变换电路，要求^大，/?。小，应选（ ）负反馈放大电路。

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SQL Error: select id,body,options from ***_enewstiku where sourceid='30217' and id < 2444237 and id<>'2444237' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku where sourceid='30217' and id > 2444237 and id<>'2444237' order by id asc limit 5