The budget crisis has forced the president to go back on his word.

预算危机已迫使该总统背离了自己的承诺。

You've always been fair and square with me, Muff Potter, and I won't go back on you.

莫夫·波特，你一向待我很公平，我不会背叛你的。

Don't go back on your word.

可别说了又变卦啊！

I give you my word and I'll never go back on it.

一言为定， 决不反悔。

He is not the sort of man who would go back on his word.

他不是那种说话不算数的人。