wich sentence is correct i am good at play the piano .and i am good at the piano

问题描述:

wich sentence is correct i am good at play the piano .and i am good at the piano
如标题 ..那个正确..为什么

只能是后一个对啊
因为be good at必须跟名词或者动名词,可以说good at playing the piano或者good at the piano