?????????????:??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????
?????????????????????:???????????????