?? ?????????????6???
????:1??????????:????
2???????
3??????????????
4???????
5?????SN????
????????????????9?????20??????????? (??????? ??)???????????4?????????????????20???????,????6????????
????,??,????????????70???????,??????,???????????1????????????????
???????,??,??,????????????????,????????4??
??,????????,??????????,??
?????????,???,????(???????) ??????????:???