He is an expert in applied physics.

He is an expert in paleozoology and has a deep knowledge about the ecology of dinosaurs.

Paleoecology is a field of study that investigates the relationship between past organisms and their environment.

Paleogeography is a study that researches the past geographical conditions of the Earth.

He is an expert in orthoepy, teaching pronunciation.

Projective geometry is a branch of mathematics that studies geometric objects such as points, lines, and planes and their relationships.

I am learning the basic concepts of differential geometry.

Computational geometry is an important field of computer science.

He is an expert in computational linguistics and is involved in the development of artificial intelligence.

He explained the importance of studying while young, saying 'If you do not study when you are young, it will be difficult to learn when you are old.'