痛改前非的英文：
[Literal Meaning]
thoroughly/correct/past/mistake
to repent one's past mistakes thoroughly

[解释]
痛：彻底；非：错误。彻底改正以前所犯的错误。

[Explanation]
to repent one's past mistakes thoroughly

[例子]
经过了这次的打击，希望他能够接受教训，痛改前非。

[Example]
After the blow this time, we hope he can learn the lesson and repent his past mistakes thoroughly.

[英文等价词]
thoroughly rectify one's errors

Jack was determined to repent of his former wrongdoings so as to redeem his reputation.
杰克下定决心痛改前非，以挽回影响。