He was once an excellent student.

He is majoring in agronomy.

He is globally recognized as an expert in epidemiology.

I am majoring in nutrition science at university.

He used a large amount of money for investment.

He used a large sum of money for investment.

He is known as a specialist in historical studies.

He is an expert in bryology and is studying many types of moss.

He is deeply interested in the study of Sō-Min rigaku.

He is majoring in political science at university.