running、swimming为什么ing前要加nn和mm

running、swimming为什么ing前要加nn和mm 为什么swimming pool,running star都有ing? which do you prefer,running or swimming?为什么动词用ing形式 swimming pool中的swimming为什么要双写加ing she always goes swimming （为什么swimming用ing形式） went swimming 为什么swim要加ing swimming lesson为什么swim要加ing He often swimming为什么要加ing she likes swimming 为什么要加ing (mm+nn)(mm+nn--4)=5,则mm+nn=?3Q My friend likes running and swimming.为什么用 running and swimmi I like running and playing basketball.为什么加 ing