?2????????????16????? ??????????,???????????????,2??16?????????20??17??????????20????????????????????,??????????????????????4~6???????7~8????;??????????????????????????????????????????????7????8??????

??:????

???????:

1?????????????????,???;

2?????????????????????????????,???????????????????????????;

3?????????????????,???????;

4?????????????,??

???????:???

??

??:???????????,??????????,??????????????