????:1??????????:???sn??

2?????

3???????

4??????????

5?????

??????8????29?????? ????,?:??????????????,???????????????????,?????????,30???,???????????????????????????????

?????:

??????????????

??????,????,???????????

????

??????????????????,?????,???????

??????????????????

??????,??????,?????

???????

??????????????????,????,???????

??????

????,??????????????,???

????

?,?????,???????

????

???????,??,????????????????????

??????????????

?????,????????,????30?????????????,?????????

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