叫什么名字并不重要.你要知道的是 at playing football表示的是He is good的哪个方面.也就是说,前者修饰的是形容词GOOD.一般我们把修饰形容词的成分叫做状语.也有人把BE GOOD AT 这样的短语看作是一个类似于及物动词来看待。后面接一个宾语。其实是一样的.不要纠结于怎么称呼了。我们还可以这样分. HE IS GOOD AT PLAYING FOOTBALL. HE IS GOOD AT PLAYING FOOTBALL. HE IS GOOD AT PLAYING FOOTBALL. 看懂了吗?
he is good at playing football
he 主语 be good at 谓语 playing football 宾语