普通单头蜗杆传动的效率一般在（ ）左右。

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SQL Error: select id,body,options from ***_enewstiku where sourceid='24893' and id < 2124453 and id<>'2124453' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku where sourceid='24893' and id > 2124453 and id<>'2124453' order by id asc limit 5