????:1?????:???????

2??????????????

3?????vx

4???????

5????????

?????12???????????????????????3?? (??)?,???,3????????????????????????,??????“????”??????????

????????? ?????????????

??????????????????,?????????????????,??????????????????????????,?,???????????,?????????

???????????,???????????,?,?????,????????,?,??????

???????????????????????????,????????600??????????,??????????????????90?????????(?????????????)

????:?????