Definition
This idiom is used to express that a kind or helpful act should be reciprocated, especially towards someone who has previously done something beneficial.
以德报德
Since John lent me his car when I needed it, I should definitely help him move when he needs it; one good turn deserves another.
既然约翰在我需要的时候借车给我，我当然应该在他需要搬家时帮助他；好心有好报。
My colleagues always offer help when I need extra hands, so when they asked for help with their presentation, I did it without hesitation. One good turn deserves another.
我的同事们总是在我需要额外帮助时伸出援手，所以当他们需要帮忙准备简报时，我毫不犹豫地答应了。好心有好报。
I once assisted her in getting a promotion at work, so she was happy to support my new project. One good turn deserves another.
我曾帮助她在工作上获得晋升，所以她很乐意支持我的新项目。好心有好报。