In a previous thread, in order to say She doesn't know what she's talking about, you would translate it to Elle ne sait pas de quoi elle parle. But, I was thinking it could be Elle ne sait pas ce dont elle parle. However, I was told that that was not French. Would someone be able to clarify? I see in a French grammar site, Je ne sait pas ce dont elle parle. What is the difference? Merci bien!!