Yet no concrete evidence of such a lake has ever been found.

But I can't be expected to act without concrete evidence.

Yet he could find absolutely no concrete evidence of any sort that would support his feeling.

There is as yet no concrete evidence to support this theory.

Come one their should be more than that particularly in view of concrete evidence.

I have no concrete evidence that they're gone or what.

You're right in saying that more concrete evidence is needed.

Not unless they came up with some concrete evidence against her.

"Then I may be able to place in your hands a piece of concrete evidence."

Is there no one against whom you can produce really concrete evidence?