Animal experiments are necessary for the advancement of science, but there are also ethical issues.

He is learning about the handling of experimental animals.

We went sightseeing in Kyoto.

He is an expert in theoretical physics.

The ejecta from the volcano plays an important role in shaping the terrain.

My pet is a dog.

The study of organic compounds is an important field in chemistry.

He is an expert in nuclear physics.

My brother is a famous biologist.

He is an expert in molecular biology.