動詞 go back on:

1. fail to fulfill a promise or obligation
   同義詞：renege, renege on, renegue on

1. In advanced years a man's mind might go back on him at some unpredictable moment.
   上了年紀的人，腦子有時候會一下子不聽使喚。
2. Don't go back on your word.
   可別說了不算數啊！
3. You should never go back on your promise to a child.
   你給孩子許了愿就千萬不要食言。
4. His father told him not to go back on his promise.
   他的父親對他說，不要違背自己的諾言。