A:①>②>③>④
B:①>②=④>③
C:①>④>③=②
D:④>①>②=③
①写出核衰变反应方程;
②算出该核衰变反应中释放出的核能.
Another new year is coming. It's up to all of us to fill it with things____ promise progress and happiness.
如图所示的光控电路用发光二极管LED模拟路灯,RG为光敏电阻.A为斯密特触发器输入端,在天黑时路灯(发光二极管)会点亮.下列说法正确的是 ( )
10个一万是____ 10个一千万是____
一百万是10个____ 十亿是10个____