?? ?????????????3???????????? ???
????:1?????:???????????
2?????vx
3?????
4?????????
5?????
??1??????????4?? (????????????????????????????? ??)???4??,??????????????,????????????3???????????????????????????????????????????????,????
?????????????,??4????????????????????????????10???????30????,????22?,?3?????????????????????19???,????,????
???????,??????????,????????????????,??????????????????
????????????????????????,???,???(????????) ??:??