This room has a dark atmosphere.

His behavior is too childish, causing trouble for the people around him.

The scent of citron is spreading, it's very refreshing.

He is a famous writer.

This email contains ghost characters.

My friend is a doctor.

A proper noun is a noun that refers to a specific person, place, or thing.

Watching the setting sun sink into the sea, I felt at peace.

I always keep an eye on the trends in the financial market.

He is an excellent student.