Georgie This is a great question and I'm sure it causes a lot of confusion! Let's try to help. Jiaying, we work for BBC Learning English, so you could say that we are experts 'in' the English language, and we are experts 'at' making teaching content. There are linguists who have spent decades studying the English language who are leading experts 'on' it.
Jiaying That's right! 先来区分名词 “expert” 后跟介词 “in” 和 “on” 时，有哪些差别。“We are experts in the English language.（我们是英语语言方面的专家。）” “Expert in + 领域、行业名称” 的意思是 “某个领域的专家”。
Georgie So, expert 'in' goes with a topic or an area of expertise, like the English language.
Jiaying 你还可以说：“an expert in chemistry（化学领域的专家）”、“an expert in law（法律方面的专家）”、“an expert in economics（经济学领域的专家）”。Let's hear some examples.
Examples She's an expert in financial analysis. （她是财务分析方面的专家。）
Both my cousins are experts in medieval history. （我的两个表亲都是中世纪史方面的专家。）
Jiaying 接下来，我们说说名词 “expert” 后跟介词 “on” 时的用法。
Georgie Now, being 'an expert on something' is very similar to being 'an expert in something'. They are often used interchangeably to mean someone is very knowledgeable about a subject.
Jiaying “An expert on something” 和 “an expert in something” 的意思很相近，两者都表示 “很懂某个领域，在这个领域经验或知识丰富”。
但相比之下，“an expert on something” 可能体现了这个人的观点更有权威性。这可能是因为这个人在该领域作出了显著的贡献，得到了更多人的认可。比如，“a leading expert on something（某个领域的权威专家）” 和 “the world expert on something（某个方面的世界级专家）”。
Georgie Yes, so lots of people might be experts in chemistry – they're specialised in and know a lot about chemistry, but fewer people are leading experts on chemistry.
Jiaying 没错，“an expert on chemistry” 的观点可能要比 “an expert in chemistry” 的观点更具权威性。听两个使用了 “an expert on something” 的例句。
Examples She is a world expert on climate change. （她是气候变化方面的世界级专家。）
He's one of the few leading experts on butterfly eating habits. （他是为数不多的研究蝴蝶饮食习惯的权威专家之一。）
“An expert at” 后常跟一个动作或行为，强调 “一个人在某个方面有高超的技能或非常熟练”。在节目开始，Georgie 说了：“We are experts at making teaching content.”
Georgie And as the listener mentioned, it's very similar to saying that someone is good at doing something, but it means they are extremely good at doing it. The verb that follows must be in the 'ing' form.
Jiaying “An expert at” 后跟动词的 -ing 形式，也就是 “an expert at doing something（做某事的能手、行家）”，它强调某人 “极为擅长做某事”，要比 “good at doing something 或 good at something（擅长做某事）” 所表达的技能水平或熟练度还要高。听两个使用了 “an expert at doing something” 的例句。
Examples The Olympic gymnast is an expert at doing double flips. （这位奥运体操运动员是跳双空翻的行家。）
My best friends are experts at making wooden furniture. （我的挚友们都是制作木质家具的专家。）
Georgie OK, so shall we summarise, Jiaying?
Jiaying Of course. 如果我们把某人称作 “an expert（一位专家）”，那么这个人 “在某个专业领域的经验或知识非常丰富” 或 “极为擅长做某事，技艺高超”。但我们需要根据 “expert” 后跟的介词来具体判断句子的含义。如果说一个人是 “an expert on something”，而另一个人是 “an expert in the same field”，那么前者的观点可能更具权威性。“An expert at doing something” 的意思是 “做某件事情的能手、行家”。问题中还提到了 “expert” 的意思是否就相当于 “authority”。虽然一位 “expert” 对某个领域有较深的了解，但只有当你的专业或学术经验被大家认可时，才会被称作 “having authority”。
Georgie Remember, if you have a question about the English language you'd like to ask us, please send us an email. Our email address is: questions.chinaelt@bbc.co.uk
