?????????????:??10???????
??? ?????2??6????18??????????????:
?,?,2?????6????????????20??8??????????????20?,??????????6~8?,??,??????????10?????????;????4~6?,????????7~8?,??10???8?,????0??????,??????????????????????????6~8??
?:
1???????;
2?????????????????????;
3?????????????;
4??????????????????
???????:???
??
???:????