"who's to know"

'who's to know'
does it mean 'who could know?'


does 'what's not to speak' mean 'what's the reason than I can't speak? I can! '


are there more expressions like that besides those above?

to be to = 1. must; 2. will

to be to = 1. must; 2. will

1. "Who's to know" means "Who knows?" as in "No one knows". "Who could know" means the same, but the speaker could also conceivably say it if they wre actually searching for someone who knows. I'm not sure where you found that expression though ("Who's to know")

2. I am confused... I have no clue what you are asking lucky.

3. Same as two.