be good at sth./doing sth:擅长于某事/擅长做某事……
be good with sb:善于应 对某人，善于和……相处。
造句:
He is good at singing.他擅长唱歌。
The mother is good with old people.这位母亲善于和老人相处。
I am good at teaching English.You are good at playing basketball.My mother is good at doing housework.我你它他她就是三个人称。
