My major is mechanical engineering.

Astronautics is a field of study related to the exploration of space and the design of spacecraft.

He is immersed in the study of geometrical optics.

My specialty is fiber optics.

He is an expert in electronics.

He is majoring in engineering.

I am majoring in electronics at university.

Demography is a branch of social science that studies the structure, distribution, and changes in human population.

In chemistry class, I learned about basic oxides.

In chemistry class, I learned about acidic oxides.