scratch my back的用法和样例：
例句
- The contract went to a friend of the chief accountant: it's (a case of) you scratch my back and I'll scratch yours.
承包合同批给了总会计师的朋友，(可谓)各有好处、 串通一气。 - Scratch my back and I'll scratch yours.
[谚]你帮我，我帮你。 - Linda asked Ham to help her with her lesson Ham said, "You scratch my back and I'll scratch yours."
琳达请诲姆帮助她做功课，海姆说：“你帮助我做，我就帮你做。”
