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

2?????vx

3???????????

4???????????

5?????

???2??????????????????2?????? ???????,??2???1???,????1?31??????????,???,??????????19???????????????????????????????????

??????????????????????????????????:???????????????????????????????,?1?????????????????31?????????????,????????????,????????

?,??????????2??????1?????,???????????????????,??????????????????????????

?,?1?31???,????????????????????????,????????????????????????????,?????

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

???????,????????????????????????2??????????????????????????????????1??????????,?????????,???????

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