I think playing basketball is boring 又不是正在进行时,为什么要加ing?

I think playing basketball is boring 又不是正在进行时,为什么要加ing? I think playing basketball is interesting里为什么play要加ing I think staying at home is really boring 中stay为什么要加ing? He likes playing basketball.为什么这里的play用的是ing形式,这应该不是正在进行时吧? My favorite sport is playing basketball.为什么加ing? I like running and playing basketball.为什么加 ing i like playing basketball 为什么play加ing My favorite sport is playing basketball 中的play后面为什么要加ing形式 i like playing basketball为什么要在play后加ing I think watching TV is boring.为什么动词watch 为什么用 ing 形式? there are many sheep eating grass.为什么加ing不是正在进行时加be的吗? he likes playing basketball.他喜欢打篮球 .为什么play要加ing