He is an expert in acoustics.

He is majoring in climatology at university.

He is an expert in limnology, and his research is highly regarded worldwide.

Demography is a part of social science that studies the structure, evolution, and problems of human population.

He is an expert in ornithology, studying types of birds all over the world.

He has a deep interest in etymology.

Let's eat lunch in the school cafeteria.

He is an expert in speleology and is exploring caves around the world.

He is majoring in meteorology at university.

He is an expert in dynamics.