?? ?????????????? ???8???15??
????:1??????????,??:???????????
2???????
3?????vx
4??????????????
5???????
?????????1???4???? ???????“????????????????????”??,????,1??????4?8??40???,?,?????????????????????????????10??10???????????????,??12?50?,????????????8????????????,15?????,?????
??
??:“?”??????? ????:????