???? ???????(????)????????????? ???? ????????.The two most common grammatical principles where by this happens is when conjugating in past times or current tenses. For examples:??? ?? ?? ?????? ?? ?? ????? ??? ?? ?? - ?????? ?? - ?? ????????? ?? ?????????? ?? ?????? ?????????? ?? ?? ?? ??? ?????? ?? ????? ?? ?? ?????????? ?? ??? ????. ?????? ?? ??