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

?????????????????????????????,??????????????????????2??????????12?17????????????,??,??61????????????????“??”????????????????????,??????

??????2??????,????2?18???????????????“??????????????????????,??????”??,?????

?,????????2?????????20??????????????????21????? ?????????:??????? “???????????”_????

?? ??????????????????61??????????????????????????????

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

2??????

3???????

4?????sn

5?????

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

?????????????????????????????,??????????????????????2??????????12?17????????????,??,??61????????????????“??”????????????????????,??????

??????2??????,????2?18???????????????“??????????????????????,??????”??,?????

?,????????2?????????20??????????????????21????? ?????????:???????