look back|looking back

回想起来，我能看到我们哪里出错了。

___Looking ___back, I can see where we went wrong.

当我回想起来时，那并不是那么糟糕的经历。

It wasn't such a bad experience when I ___look ___back on it.

当我回想起我们一起度过的那个夏天时，我感到痛苦，有时会泪流满面。

When I ___look ___back on the summer we spent together, I feel miserable and sometimes I burst into tears.