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.

Do you remember where I put my study guide?

He is an expert in Classical Chinese text studies, and is good at interpreting ancient Chinese literature.

He understands the basic concepts of thermodynamics.

Spectroscopy is an important means of investigating the properties of matter.

He is knowledgeable in all fields of learning.

He is widely recognized as an expert in dogmatics.

He is majoring in the study of national law.