我本想告诉她你打过电话，但我完全忘记了。

I meant to tell her you had phoned, but it completely ___slipped ___my ___mind.

有件事，但在我到达之前就忘记了。

There was something but it ___slipped ___my ___mind before I reached it.

有时，即使是最重要的事情也会被忘记。

Sometimes, even the most important things can ___slip ___your ___mind.