潘婕的回答：

后悔莫及: 1. too late to repent http://sh.dict.cn/search/?q=%BA%F3%BB%DA%C4%AA%BC%B0&r=%CB%FB%BA%F3%BB%DA%C4%AA%BC%B0

殷琦的回答：

后悔莫及: 1. too late to repent http://sh.dict.cn/search/?q=%BA%F3%BB%DA%C4%AA%BC%B0&r=%CB%FB%BA%F3%BB%DA%C4%AA%BC%B0

very的回答：

后悔莫及的英文 后悔莫及 [词典] too late to repent; cry over spilt milk; repent when too late; you will be sorry when it is too late; one's remorse will be too late;

朱婉清的回答：

He regreted a lot but has no idea.

管婷婷的回答：

He regretted, but it was too late.