Does it make sense?
Hello, I have a question.
In my study group, we talked about our hometown.
I came across a guy who knew about bio-industry.
He explained what's going on in bio-industry.
At that moment, I told him "You're really in the know about bio-industry."
Does it make senese what I said in that situation.
If it doesn't, could you give me another one?
How about these expressions like "know something inside out" or
"know something like the back of one's hand"?