不是哦!an 【eleven-year-old 合成形容词,只做前置定语】boy=a boy【 of eleven years old 介词短语,作后置定语】an eleven years old boy 表达形式错误,因为【eleven years old 】可以作后置定语（与of连用）、表语...那one eleven-year-old boy的同义句是什么one eleven-year-old boy=aneleven-year-old boy=a boy【 of eleven years old 介词短语，作后置定语】