2???2????,????,??“??”“?”????????????,????? ????????????????????? 2????2????,??,??“?”“???”?????????????????????????????????,????????? ???? 2?????2?????????????????????,?????????????????????????????,???“?”“????”??????????????,??????????????????????????????????????? ? 2??2??,???,?????????“?????????????????????”“???”??????????????????????????????????????????,??????? ????????? 2?????2????,??,?????“???”“?????????????????????”???????????????????????????????????,???????????????????????????????? ???? 2?????????2?,??,?????????“?????????????????????”“??”????????????,????? ? ??????????????????????:?? “??????????”_????

?? ????????????:????

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

2???sn

3???????

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

5????????????

2???2????,????,??“??”“?”????????????,????? ????????????????????? 2????2????,??,??“?”“???”?????????????????????????????????,????????? ???? 2?????2?????????????????????,?????????????????????????????,???“?”“????”??????????????,??????????????????????????????????????? ? 2??2??,???,?????????“?????????????????????”“???”??????????????????????????????????????????,??????? ????????? 2?????2????,??,?????“???”“?????????????????????”???????????????????????????????????,???????????????????????????????? ???? 2?????????2?,??,?????????“?????????????????????”“??”????????????,????? ? ??????????????????????:??