?? ? ??????5.4??????????
????:1????????:?????????????
2???sn??
3?????????
4????????
5?????
?11??????????22?? ??,????22??????????,??????????????????5.4?,???“???????????”?
????,?22?18??45??????????20???22??20?40???20?43???21?????29?????????,?20??40?5.4?????,??????????23.2?????120.18??,?????23.2????????????,?7.7????????????????
?????????,?,????????????????????,??,?????“????????????”??,???????
?????????????,??????“?”,??????????“?????????????”?
????,22?20??????????40???????4.7??????(???) ??:????????????????????