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

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

3?????vx

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

5????????

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

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

???????????,????????????????????????,??????????????????,????????????????????????????????????????,?????????????,????????60?????????,????????????????

?????????????????????,???;???,???;?????????????,???????90%?

??,“????????”???????????????????????,????????,60?????????????????34%,???????????????????????

???,????????????,??????????,?6????,????????????50%?????????,????“????????”?????????,????

?????????????,2??????????????5????????,????????????????????24%? ????????????:????