“be good at”是一个英语句型，意思是“擅长于某事”。它可以用于表示一个人在某方面有较高的技能或才能。
“be good at”的构成是：be + good + at + 名词或动名词。
肯定句：主语 + be + good + at + 名词或动名词
否定句：主语 + be + not + good + at + 名词或动名词
疑问句：be + good + at + 名词或动名词 + 主语 + ？
例如：
肯定句：
I am good at playing the piano.
She is good at cooking.
They are good at swimming.
否定句：
I am not good at math.
She is not good at driving.
They are not good at dancing.
疑问句：
Are you good at playing the guitar?
Is he good at singing?
Are they good at playing basketball?
“be good at”还可以用于表示一个人在某方面做得好。例如：
He is good at his job.
She is good at studying.
They are good at solving problems.
“be good at”是一个比较常用的句型，在日常口语和书面语中都很常见。
