Man, these forms are kinda outdated, someone may even blame you for using that.
Russians say: намешай бетона, насыпь сахара (сахарка, сахарку - уменьш.-ласкательная форма), отрежь сыра
"Насыпь сахарку" somehow is the only one of these which is still active.
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 woulnd`t even get what are you talking about even mentioning "partitive". Just learn these common phrases by heart and that`s it.
Съешь ещё этих мягких французских булок, да выпей чаю - well known joky phrase among russian pc\ms word users (since it contains the majority of russian alphabet)
Съешь ещё этих мягких французских булок — Lurkmore