I don't profess to be an expert in this subject.

我不敢自诩为这方面的专家。

《牛津词典》

You do not need to be an expert in color theory, but it's good for business professionals to know at least a bit on the subject.

您不必成为颜色理论专家，但作为一个商务人士，了解一些色彩知识是很有好处的。

youdao

He claims to be an expert in astronomy, but in fact he is quite ignorant on the subject.

他声称自己是一名天文学专家，但实际上他对这门学科相当无知。

youdao