He was terrified of living in a police state.

After finishing reading the official documents, he thought deeply.

A ray of morning sun came in through the window.

All students at this school are enthusiastic about studying.

He is an expert in public law.

This antigen triggers a specific immune response.

This tank has strong armor.

He was clad in armor all over his body.

This vaccine contains the antigen of the new coronavirus.

A binary operator is one of the basic concepts in algebra.