swim 为什么这在进行时 变成swimming?

swim 为什么这在进行时 变成swimming? swim为什么变成swimming? 为什么swim的现在进行时是swimming.play的现在进行时是playing? swim为什么写成成现在进行时要双写?swimming? My father helps me with swimming.为什么这时候swim要变成swimming? 为什么swim变正在进行时变swimming而不是swiming swim要怎么变成现在进行时啊~ went swimming 为什么swim要加ing swim team为什么不是swimming clud? go swim还是go swimming 为什么 swimming is my favorite.为什么不是swim swimming lesson为什么swim要加ing