a quesiton

[light]

hello,
"She is expert in drafting the minutes of a meeting." Why there is no an before expert? And don't we use the preposition at with 'to be an expert' ?

[jrherring]

From the form of the sentence, I would think that "expert" in this context would be an adjective, as in "expert system." If used as a noun, it would use an article ("an" or "the" depending on if she was just one of many or the best) but the meaning would not really change much, except for the implication of degree of expertise.

[light]

I didn't know that expert is also an adjective. thank you.