The only sure way to know is to flight test them.
There was one sure and certain way to find out.
But living in the past was one sure way to become part of it.
It was a sure way to be free of them.
He was not at all sure one way or the other.
"There is no sure way except to bring you back with me."
At the moment, he saw no sure way of doing that, either.
And there was only one sure way of doing that.
There was only one sure way to clear his head.
Seemed like a sure way to get killed out here.