We'll start with two things we do know for a fact.

No one had ever heard the like, but everyone took it for fact.

I know this for a fact because I've seen him on tv.

He knows for a fact that I want him to leave.

For a fact, I never saw her the whole time we were there.

I know for a fact that you are not, and never have been, one of us.

I could tell he did not know that for a fact.

I know for a fact you are working to control the size of the field.

Which he knows for a fact she does not spend on the child.

These are things that most of us know for a fact and don't question.