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

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

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

???????:?? ??“????????”????

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

????:1?????????:????vx

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

3???????

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

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

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

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

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

???????:??