He would be making a terrible mistake to think they will just go away.

I think the war in Iraq is a terrible mistake.

I wanted to tell him he was making a terrible mistake.

I felt as if we had made a terrible mistake.

So who's to say it was all a terrible mistake?

Meeting his eyes was a terrible mistake the second time, too.

But how can I let him make such a terrible mistake?

I made the terrible mistake of not reading the program before the show started.

The only way would be to make a terrible mistake.

He felt the change in plan was a terrible mistake.