????:1???????????:??????

2?????????

3???????sn

4?????????????

5??????

?????“???”????? ? ?? ????«???»?«?????»??????????????????? ?? ???????? ???????????“??????????”???? ????? ?? ??????????????“?????”?????????? ?? ????? ?????????????“??”????????????? ????? ????????? ?????«?»??????????? ?? ???????? ????????????????“??”(????)??????????? ????? ????? ??:?????????