You may be sure in your heart, but that's not how law works.

One could never be sure of anything in this life.

Also, we cannot be sure in what direction they now are.

You could never be sure in a situation like this.

Are you quite sure he is right in the head?

You can never be sure of anyone in the industry.

I've never been so sure of anything in my life.

But it sure sounds serious, like everything in the film.

She found one at last that seemed just right, although it was hard to be sure in the dark.

It will happen, although I'm not sure in what form and how.