????2???????????21?????????? ?????????????:???????2???20?????,????,?????????????????????????????????????????,?????????????????99.9%???,0.1%??????????????

?????????????????????????

???????????????????????????????????????????,????????,??????????????????,???,????????????,?,???????

?«?????????»????????,???????????????“?????”?????????????,??????????????????????????,?,?????????????,????????????

????,???(??????) ???:????? “???????????”????

?? ????????????? ????99.9%??

????:1????????????:?????95?98?

2????????200??????

3???????

4??????????

5???????

????2???????????21?????????? ?????????????:???????2???20?????,????,?????????????????????????????????????????,?????????????????99.9%???,0.1%??????????????

?????????????????????????

???????????????????????????????????????????,????????,??????????????????,???,????????????,?,???????

?«?????????»????????,???????????????“?????”?????????????,??????????????????????????,?,?????????????,????????????

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