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

2????400??

3???????

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

5?????

??1??????????????????30??????? ??????(NBC)30????????,?????30???????????????29?,????????????,?“????????”???????????????????????

??1????29??,???????????????,????????????????????????1?30??????? ???? ?

??????????????????????,?60?????4???????,????????????3??

????????????30???????????????,?3???,???300?,?????????,?????

NBC??????????????????????,???????,???

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