He is majoring in geology.

He is an expert in pathology.

I am majoring in information science.

He solved the problem in a scientific way.

I study Japanese every day.

This reaction occurs through a chemical process.

He is an expert in virology.

He has a deep interest in teratology.

I am majoring in embryology at university.

He is an expert in embryology, studying the developmental processes of many kinds of organisms.