Спасибо всем за чрезвычайно чёткие(< google/the site marks this with a green "incorrect grammar" line) ответы

xXHoax, Why would you overload your brain with this issue? I have passed my school Unified State Exam on "A" mark and we had no hours dedicated to the subject, nor my personal coach gave me any of that theory. 9 of 10 of russians wouldn't even get what are you talking about even mentioning "partitive". Just learn these common phrases by heart and that's it.
Эти вопросы, честно говоря, произошли из места интерес вообще в языках вместо интереса в изучении русского.