?? ????????? ?????????????
![](https://image.chezhanri.com/2019/1109/73a4bcacae9399fc63913355faa62266.png)
????:1???????:??????????
2????????sn
3????????
4??????
5?????????????
8????????10??????,??????
????,????«??»«??»«?????????????????????»«??»??????,???,??????????????????,??????????,????????????
????,???????????,?????????????????????????????????????????????????????????????,????,?,?????????????????????????????
?,????????????????,????,???????????,???????????????????????????(??? ? ??)
????????:????