— ____ do you like P. E?
— Because it's fun.
A:Why
B:Who
C:How
D:When
关于聚落的发展变化,下列认识中不正确的一项是( )
某个光子是氢原子核外电子从n=4跃迁到n=1时所发出的,已知普朗克常量h=6.63×10﹣34J•s,求: