This is the biggest flood in a century.

That you are a once-in-all-history event.

We suffered a rare financial and economic crisis in the past year.

He' s the kind of player that comes along once in a blue moon, a play maker whose vision, passing and inventiveness makes a huge impact on any game he plays in.

At the start of 2011, we' re still just emerging from a once-in-a-lifetime recession that' s taken a terrible toll on millions of families.