加工a = 20°的正常标准直齿圆柱齿轮时，不产生根切的最少齿数为（ ）。

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SQL Error: select id,body,options from ***_enewstiku where sourceid='24894' and id < 2124494 and id<>'2124494' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku where sourceid='24894' and id > 2124494 and id<>'2124494' order by id asc limit 5