?6?????12????? ??????????6????????12????,??????????????

???????????????????????,?????????????????????:????21????,?????????????,“??????????”,?“??”,??????“????????????????”?????????????????????????

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

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

?? ???:“??”???????????????????????

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

2???????vx

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

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

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

?6?????12????? ??????????6????????12????,??????????????

???????????????????????,?????????????????????:????21????,?????????????,“??????????”,?“??”,??????“????????????????”?????????????????????????

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

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