"You never know ..." is impersonal, the same as "One never knows".
"You'll never know" is addressed to a specific person.
Man to Lady: "I think you'd look great in that lingerie."
Lady: "You'll never know".
Yes, you right about the first three needing "You".
So is it applicable in this conversation?
Kid: I hope I can graduate next year and finish all my requirements.
Mom: You never know what will happen next year.
Thank you.
No, you can't. You could say "You'll never know unless you ask her.""You'll never know, she might say yes."
So I cannot use "you'll never know" in this context?
"You'll never know, she might say yes."
So I cannot use "you'll never know" in this context?