Heaven knows! spoken
God knows! spoken
goodness knows! spoken
who knows! spoken

Heaven knew what they were going to do with all these people.

Heaven knows, she might have set her mind at rest, poor child!

She tried hard enough, heaven knows, but of course he was never in love with her.

But heaven knows what I'm going to look like after tonight.

Heaven knows what will be the result of all this!

Heaven knows there are enough of those around, but you're something special.

Heaven knows I never thought 'just in case' would include getting shot at.

Heaven knows, I'd find it hard to make myself without half an hour or more of serious thought.

Heaven only knew when he would have time for this again.

Heaven knows how beautiful they may have been at one time.