He is an expert in toxicology and conducts many studies.

He is majoring in zoology at university.

I am majoring in biology at university.

He is an expert in theoretical physics.

He couldn't say anything about issues outside of his field of expertise.

There are many different specialty stores in this town.

He is a specialist fool, with no interest in anything outside his field.

She is planning a date with her current boyfriend.

He lost everything.

My boyfriend gave me a gift.