You don't say ! I never expected you to win the competition.

I can't say for certain whether the weather will improve this week.

As I was saying, we need to focus more on our marketing strategies.

As the saying goes, "Nothing ventured, nothing gained."

I would go so far as to say that she is the most talented person I know.

You can say that again.

I guess you could say

I suppose you could say that I'm a bit of a perfectionist.

She expressed her disappointment without saying a word.