蜗轮齿圈常用青铜制造，是为了（ ）。

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SQL Error: select id,body,options from ***_enewstiku where sourceid='24893' and id < 2124467 and id<>'2124467' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku where sourceid='24893' and id > 2124467 and id<>'2124467' order by id asc limit 5