swim为什么变成swimming?

swim为什么变成swimming? swim 为什么这在进行时 变成swimming? My father helps me with swimming.为什么这时候swim要变成swimming? went swimming 为什么swim要加ing swimming lesson为什么swim要加ing go swim还是go swimming 为什么 swimming is my favorite.为什么不是swim swim team为什么不是swimming clud? swimming ＆ swim可以说 (swim team) (swimming team)为什么只能说（swimming club）不能说（swim club） Rose often goes to____on Sundays.But now she is______.A.swimming,swimming B.swim,swim C.swim,swimming D.swimming ,swim原因，为什么 swim------swimming,write-----written,swim------swimming,drop------dropped,为什么它们变形都要双写两个字母? lets go (swimming/swim)为什么要选swimming 而不选择swim swim team 和 school swimming team为什么一个是swim,一个是swimming呢? swimming club 中的swim为什么要用ing形式? swimming club 中的swim为什么要用ing形式? I have a swimming lesson为什么swim用ing形式 为什么swim变正在进行时变swimming而不是swiming 为什么 I'M GOING SWIMMING 不是 TO SWIM?