????:1?????vx:?????

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

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

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

5???????

???????????????2????????????????21???????????? (??????????????)???????????????21??,??,?????????,??????????,?“????”???????,?????

?????????????????????????????,????????????????????????????????????,?????????,??;??????,????“?????????”??,?????????????????;??????????????????????,?,??????????

??????????????,????????????????????????????????????????????,???????????????,??16??,??????????23???,??????13?????????????????35???????????45??,???50%?

??,???????????????????,???????;??????????????,??????????????????????????,????????????1?,?????????(??) ???:??????????????????