一、be expert in 翻译及例句
be expert in：在……方面是行家等含义；
例句 1. she is expert in education.
她是教育专家。
例句 2. Travel them, and be expert in home-cosmography.
那末去旅行，成为家庭宇宙志的地理专家。
例句 3. I want to be an expert in my own field.
我要在自己的`领域成为专家；
例句 4. I hope I will be an expert in this field.
我希望在未来成为这方面的专家。
例句 5. She is supposed to be an expert in this field.
人们认为她在这方面是专家。
二、be expert at 翻译及例句
be expert at：精通等含义；
例句 1. she is expert at teaching students.
她擅长教学生等等。
例句 2. Competent scientists, however, must be expert at changing their minds.
然而，有能力的科学家必须善于改变看法。
例句 3. They have to be expert at dealing with any problems that arise.
他们必须善于处理随时发生的各种问题。
例句 4. I decided to be an expert at solving this problem.
我决定成为解决这个问题的专家。
例句 5. No matter what, I'll be an expert at what I do.
无论无何，我都会成为我那一行的专家。