it's no matter what they told if it is false but you have a very sure evedence that make told you that is true
if you're talking about the big three words (" I love you") then i can give you some advice on if "he" really meansit. well, it's like you can actually feel a certain warm vibe coming from him when...
You can tell by the way you talk and the way you answer to other people . That's how you know
When somebody insults you, for example calls you fat, say it and I means yes you are fat but what about me.
To understand or "know" what you are talking about. It means that you have inside information on something, a secret or a hot tip.