?? ???? ???????? ?????? ????????? ?? ??????.If a grammatical principle that's included to ????is often a vowel ??and there's no other selection apart from a vowel ??then that grammatical principle can't be included to ?????? ???? ??????, ????????????, ???? ???? (???????? ??)???????? ???????? ????, ???????? ?????? ????????? ???????????? ???? ????.??