?? ??????)??????? ?????? ?? ????, ??, ?? ?? ????.The 2 most popular grammatical rules where this happens is when conjugating before or present tenses. For illustrations:- ???? ??: ??, ??, ??(??, ???????? ??), ??????, ??, ????????????? ???? ?????????????? ??????????????? ???? ?? ????????? ???? ???????? ???? ???? ????????. ?????? ?????? ???????? ????