He is the main organizer of this event.

He is a very excellent technician.

He is a world-renowned researcher.

The operator is operating the machine.

He is already an adult, so he can make his own decisions.

The police are looking for an eyewitness to the incident.

The police arrested the suspect.

The intellectuals deeply discussed this issue.

The criminal was arrested by the police.

I am the person in charge of this project.