うっかり忘れてたんだよ。の英語

It must've slipped my mind.

I completely forgot.

I completely forgot it.

I've clean forgotten.

I completely forgot.

Maybe he forgot.

I completely forgot it.

I've become forgetful.

I inadvertently forgot about that.

I completely forgot it.

I've totally forgotten.

I was forgetting about that.

Oh yes, I remember

I had quite forgotten it.

Yes, I had forgotten all about it.

I forgot it.

I have forgotten all about it

It has completely passed from my memory.

I completely forget it.

I completely forgot it.

I almost forgot all about that.

That has been forgotten about.

Apparently, you forgot these.

That had escaped my memory.

I was forgetting about that.

I thought that you might've just forgotten.

I thought you might've just forgotten.

You might have just forgotten.

I had clean [quite, completely] forgotten it.

It must've slipped my mind.