???????????2???????????20???? ???????????,?2??20??,????????????(????????????????????)??????,?????4????

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

?????????????,???4?,???DNA?,???????????

????:??????????? ??“??????”

?? ???????????4?????

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

2????????????

3?????WX

4?????

5??????????

???????????2???????????20???? ???????????,?2??20??,????????????(????????????????????)??????,?????4????

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

?????????????,???4?,???DNA?,???????????

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