?????? ?? ?? ?? ???? ???????????? ??????????The two commonest grammatical ideas in which this happens is when conjugating in the past or current tenses. For examples:???? ??????? ???????? ???????. ??? ?????????(??)?? ?????? : ??, ??, ????, ??, ???? ?·???????, ?? ?????? : ?????? ?????????? ??·??????????? ??????????? ?? ?????????? ?? ?????? ???????