???? ???????? ????????? ???? ???? ?? ???The 2 most popular grammatical principles where by this occurs is when conjugating in the past or present tenses. For illustrations:???? ????? ???? ???? ???????? ??????????????- ???? ?????????? ???? ???????? ?????????? ??????????? ????????.???????? ???? ???????? ???? ???? ????????. ?????? ?????? ???????? ????