?????????12?????????????20???? ?????????????????????20????,?????????,“??????????????”???????????????????,?????????????????,??????“??”???????????

????,???????????,????????????????,????“???????”?,??????“????”??????????????????????????,??????????4?????:????;??;????;????

??????????????????????????:??? ??“????????”

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

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

2?????vx

3?????

4??????????

5?????????????

?????????12?????????????20???? ?????????????????????20????,?????????,“??????????????”???????????????????,?????????????????,??????“??”???????????

????,???????????,????????????????,????“???????”?,??????“????”??????????????????????????,??????????4?????:????;??;????;????

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