"You don't know her."
Translation:당신은 그녀를 몰라.
I think this example shows the disrespectful use of 당신 which explains the casual impolite form
Isn't 당신 too formal and 몰라 too informal?? Dear Duolingo, this is getting confusing!!
From what I've heard 너 is impolite in most situations. Although I've also heard that hardly anyone says 당신 outside the dramas...
I heard it at a wedding, during the vows, but that makes sense in that context
Is "몰라" informal? We haven't learned this yet so why is it thrown in there.
Yes. Its not a bad idea to use other resources to learn stuff besides duolingo. Removing 다 and adding 어 or 아 to the verb stem is the way to conjugate to the informal form.
Dongsa.net is a great resource if you want to see all the conjugations for a verb, or see what the dictionary form of a conjugated verb is.
This sounds like in the Korean drama..... "You ain't know that lady. She's mine"