?? ???????????????
????:1?????????????:???????vx
2????????
3????????
4???????
5??????????
?1?7??????????? ?,?????????6.8?,????????,????????
??,?????????????????????10????????????????????1??????????;10~20????????????????1???;20~50???????4?????????4?????????????1?????????????7?????10????????????43???????????,????
?????????????????????,??????????????,????
??:???????????