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

2?????sn

3?????????

4??????????

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

?????????????????6????????????????15????? (?? ???????)14?????15?????,?????????????????????????????,?213.8??

???,14??8????????15????????8?????????,??58??100??,??305?????50??100??,??:?178.5?????????????153?????????????145.5????????136.7??????

???????????,15??????????????????????16??,??,?????????????????????7?9??;15??,??????????????????????????????,????????????????????????????;16??,????????????????????????(?)?,???17???????20???????,??????????,????????????

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