“擅长于”的英语是be good at 。
be good at 意思是“擅长于……”，后跟名词、代词或动词ing形式。be 随着人称和时态的变化而变化。如：1. He is good at English。他擅长英语。2. She is good at singing。她擅长唱歌。3. They are good at playing basketball。他们擅长打篮球。4. Jim was good at drawing when he was ten years old.。吉姆十岁时擅长画画。5. Lily's favourite subject is maths and she is good at it 。李利最喜欢的科目是数学，她很擅长它。
女王大人过司考
