be good at ; be good with; be good for 用法

1. be good at (doing) sth. 擅长于……

e.g. She is interested in painting and she is really good at painting animals. 她爱好画画，并擅长画动物。

We are very good at math and we have fun learning it. 我们都擅长数学，学习数学很有乐趣。

2. be good with 善于应付……

She volunteers at the Old People's Home and she is good with the old people. 她在老年人之家当义工，她跟老人们相处很有一套。

3. be good for 对……有好处

Eating too much ice-cream is not good for our health. 冰淇淋吃得太多对我们身体不好。