She is under an obligation to her adoptive mother.

她有义务赡养她的养母.

《简明英汉词典》

Her adoptive mother was a housekeeper.

她的养母是一位管家.

《简明英汉词典》

Her adoptive mother treats her better than her biological mother.

养母对她比亲生母亲还要好.

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Please return after the adoptive mother , did not return subsequently.

后请归养母, 遂不复出.

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He always provides for his adoptive mother as if she were his biological mother.

他一直把义母当成自己亲生母亲来赡养.

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