当我想起你们俩发生的事情时，我忍不住笑了。

I ___can't ___help laughing when I think about what happened to you both!

我忍不住去想发生了什么。

I ___couldn't ___help thinking about what had happened.

我太难过了，忍不住哭了。

I got so sad that I ___couldn't ___help crying.