be good at 表示"擅长……",后面接名词或动名词 (V-ing)。
✅ I am good at Science. 我擅长科学。(接名词)
✅ She is good at doing experiments. 她擅长做实验。(接 V-ing)
✅ He is good at using computers. 他擅长使用电脑。(接 V-ing)
I → am | He / She → is | You / We / They → are
I am good at History. 我擅长历史。
He is good at Geography. 他擅长地理。
They are good at I.T. 他们擅长信息技术。