It proved impossible, however; the matter was too big for us.

It proves impossible to get any information at all from them.

Despite some efforts being made to save her, it proved impossible.

And when that proved impossible I wanted to kill you.

If she is already dead then it will prove impossible.

This has proved impossible to do, as the answer is both.

I tried to find him over the years, but it proved impossible.

Was it that they did in fact prove nearly impossible for him to get his hands on?

Only on one particular point did it prove impossible to reach an agreement.

The only major market where the approach has proved nearly impossible is Japan.