We'll know for sure once the test results come back.

Until we know for sure, you stay well away from him.

Maybe both of them would like to know, for a price.

And no one knows for sure what she might be.

But the only way to know for sure is to try.

Then you never knew for sure what death was like.

Who knew what the future held, for any of them?

Even though she knew him for what he was then.

I know you were in here last week, for example.

But they had told him what he'd wanted to know for years.