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

2?sn???????

3?????????

4?????V

5??????

?9?????4??????????? (?)???????????????????????????????4???,?????????4???,???3??1???

9???4????????????????4???,???,????????????????????,???????????3??1???,???,???????????????????,?????

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

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