be grateful to sb and seek ways to return his kindness ? 他們救了他的命，他怎能不～。They saved him. He was grateful to them for his life and would surely seek ways to return their kindness.
感恩圖報ɡǎn ēn tú bào
感激他人恩德，謀求報答。be grateful for, be grateful to sb. and seek ways to return his kindness, feel grateful for a kind act and plan to repay it