The concept of topological space plays an important role in many fields of mathematics.

He is working in the field of science.

This concept is difficult.

Topology is a branch of mathematics that abstracts and generalizes the concept of space.

He reads a lot of books.

He spends a lot of time studying.

He worked hard to accomplish his goals.

His role is the team leader.

Health is very important.

His opinion is very important.