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

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

3?????SN

4??????

5??????????

???6????13?? (?? ???????????????????????)13?19????55?????????,???,??2?????????,?????????60?80???,??????????????,3??100??,?????

???? ??

??17??????,13????????14?????????,??????????????????????????????????????????,??,????14??15??,???????????????????,???15???16?,?,????????????????????????????????????,?????

????,???12?,???????????,????????6????????????????13???????8????????????16??8??,??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????(???????)?(??)

??:???