be devoted to.致力于…(devoted为形容词化的过去分词,不存在被动关系,就想be interested in/ be satisfied with等一样）
在此作原因（或伴随）,【由于缺乏语境,不能完全决定.】
相当于：As/ Because she was devoted to her mother,she looked after her for many years.
想必你能理解为何是【动宾关系了吧】
楼上在忽悠!