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

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

3???????

4?????vx

5????????

?????(?????????????????):?,??????????,??????????????????????????????,???,??

??????????,???????,??60%???,????????????????????,??

??????????????,??????1800?????????????????????6?????????6?????????,?6??????

????????,?????????????????????????,?????,?????800??????????

???????????????????????????,??????????????????????,??????????,??????21??????

6????????15?????????,??,??,?????????????,????????????????????????,?????????74??85%?????????

??????????????(6???????16????)?????????????,????417?????????,????13????????,?????????????????,?????????? ??????????????:????????????