??? ?????? ????????? ???? ?????????? ????The 2 most frequent grammatical rules in which this occurs is when conjugating prior to now or existing tenses. For examples:?? ???? ??????, ????????????, ???? ???? (???????? ??)??(??)?? ?????? : ??, ??, ????, ??, ???? ?·???????, ?? ?????? : ?????? ?????????? ??·??????????????????????????? ???????? ??????