He is an excellent chemist who made many discoveries.

He was feared as the dictator of that country.

He is a powerhouse in the company.

He is the main performer of this project.

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.

He is a very talented arranger.