如果你go back on your word，意思就是你“出尔反尔，违背诺言，食言了”。

例句

I’m sorry to go back on my word but I can’t write you a reference after all. Your behavior recently has been very poor.

I’m sorry to say the builders have gone back on their word. They had promised to finish the kitchen by the weekend but now they say they won’t be able to do it until next week.

请注意

另一个英语表达to give someone your word意思是“给人承诺”。

例句

I give you my word that it wasn’t me who broke your laptop.

She gave me her word that she wasn’t seeing anyone else. I believe her so the wedding is still on.