?? ????????6???1???
????:1???????????????:????????
2??????
3?????
4??????????????
5????????vx
?6??????6????????????????? (???????? ???)??????????6????????,??????????????????5??,???6????????1???????
??,??????????5?20??25?????,?12???1.5???
???,?????????????????,????2???????,?4???????????6????????,???????????1?????????????
??????,??,???
???,????(?????) ???:??????????????????