翻译是Looking back the past things，He is greatly indebted to his parents。还可以翻译成In retrospect of the bygone things，He is filled with much gratitude for his parents。回首往事的英文是In retrospect，recall the past。

回首往事的例句：

1、回首往事，我觉得当时我错了。

In retrospect，I think that I was wrong。

2、她回首往事毫无遗憾。

She looked back on the past without regret。

3、如今回首往事我已不再感到悲痛，并且开始展望将来。

Now I can remember without mourning，and begin to look ahead。

4、长大后，每当我们回首往事时，我们都会希望当时做出了更好的选择。

As we get older，we look back and wish that we had made better choices。