- ??? ????(????? ??)???? ?? ????????? ?? ???? ??.The 2 most typical grammatical rules where by this occurs is when conjugating previously or current tenses. For illustrations:????? ??????????? ?????? ?? ?????? ?????? ???????? ???? ????, ?? ?? ???????????????????? ?????? ?? ????.?????? ???? ?? ???? ??? ?? ?? ?????? ?????? ?????? ???? ???????? ??????