must - ??????? ???????????????, ??????????? (I must attend this meeting) should - ????? ????? ???????????????? ????????, ????? ?? ???????? ? ????? "???????" (You should study more) have to - ????? ?? ?????? ???-?? ??????? ?? ??????? ????? ??-?? ??????????? ?? ??? ????????????? (Time's running out, I have to go)