????:?????
??“????????”????
??????
????????
??????
??????
??????
??????
??????
??????
??????
??????
??????
??????
??????
??????
??????
??????
??????
??????
??????
??????
??????
??????
??????
??????
??
?????? ?????????“??”
?????? ?????????“??”
??
????:
1?????????:????sn
2??????
3??????
4??????????
5????????????
????:?????
????
6
%
???:??