be good at something用法例句：
1. If I were going to be good at something, I had to be the best.
2. I wondered if I could be good at something.
3. If Bill Gates was going to be good at something, it was essential to be the best.
4. Learn to paint, dance or anything else you've wanted to do. It's always fun to have an interest and be good at something.
5. Therefore, if you want to be really good at something, you have to first set a goal and then put in the hours to get there.
be good at doing something用法例句：
1. I didn't think Chris would be any good at fund raising for the society, but she seems to be doing a good job.
2. But I think to be good at anything you have to have drive and passion, and you want to be perfect is with what you are doing.
3. Only through repeated practice can one be good at doing things.
4. An example would be a basketball player who isn't very good at free throws spending hours and hours just doing free throws while being coached. Not a great time no matter how big of a basketball fan you are.