This old radio uses a vacuum tube.

My new living space is very comfortable.

He is excited about living in outer space.

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

The prevention of venereal diseases is most important in safe sexual behavior.

He decided to have a vasectomy.

His view of life is very positive.

His thought is very unique.

He has an illustrated reference book of insects.

The government is building a nationwide surveillance network.