用数学归纳法证明“当n为正奇数时，x n+y n能被x+y整除”，第二步归纳假设应写成 （    ）

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SQL Error: select id,body,options from ***_enewstiku_ where sourceid='19761' and id < 1715255 and id<>'1715255' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku_ where sourceid='19761' and id > 1715255 and id<>'1715255' order by id asc limit 5