He is writing a thesis on paleogeography.

He claims to be a warrior for freedom of expression, but in reality, he's just someone who uses derogatory words.

He is working as an agent for the Central Intelligence Agency.

By regularly checking the key performance indicators, you can understand the performance of the company and devise improvement measures.

He is majoring in linguistics.

He has a deep interest in astronomy.

He is an expert in physics.

Electromagnetism is a part of physics that studies the interaction between electricity and magnetism.

He is good at solving geometry problems.

He is an expert in toxicology and conducts many studies.