Noun declension - Accusative case.
My question is about Noun declension of the accusative case. I recently found out about accusative declension of animate and inanimate objects. So, a sentence like
Я знаю Иван becomes я знаю Ивана.
My question is why is the sentence это наш друг not это наш друга?
This might sound strange, but is it because it's a subject predicate not the object of the sentence?