??:7????????? ??????7?8?

??

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

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

?????????:

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

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

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

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

??????:??

?????????

???????:7????????? ??????7?8? ?????

????????