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

2????????????

3???????????

4???sn??

5??????????

??2??11?? ??????????????11??????????,????????,?????????????????????

2?????1??????????????2???????5?,?????????,?????????46???103?????????????????,?????????,????????????????????????????????????????????????????5???????????????????

????,??B??????????,?C?????,?A????11??????????1??????3??????3?????????

?,?,?????????(???????????????????????????????) ???????????????:??