"He knows this girl."
Translation:Он знает эту девочку.
so every time there is a Direct object pronoun it always takes the genitive case? - Or some other case? Does nomitave not exist when using verbs on objects?
он - nominative (the subject) эту - accusative (modifies the direct object) девочку - accusative (the direct object)
Yea i know what modifying is. My question is only specific verbs make these objects change cases? I've been studying Russian for a while on and off and when to use the cases has been the biggest challenge.
I think your confusion probably comes from masculine nouns where the accusative of inanimate nouns matches the nominative, and the accusative of animate nouns (people, animals) matches the genitive.
Он знает этот дом
Он знает этого мальчика
Both are in the accusative, but they don't look like it.
(Edited to fix этот to be correct - it also matches the nominative/genitive in the same way)
it's a little odd, it's like saying "this girl, he knows", but it's not incorrect
эту девочку он знает // знает он эту девочку // эту девочку знает он
etc. all are correct and can be re-arranged based on what you want to emphisize