I changed my clothes in the changing room.

He was waiting for the guests in the guest room.

He was reading a book in the reading room.

It is his habit to read books in the reading room of the library every day.

He entered the confessional of the church.

I'm going to the nurse's office because I have a headache.

He is operating the equipment in the control room.

His left ventricle is functioning normally.

His right ventricle is functioning normally.

I'm looking forward to watching the new movie in the screening room.