Naphthyridine is one of the important compounds in organic chemistry.

Phthalazine is a compound often used in organic chemistry.

Expanding your network is very important in business.

He has a Polish friend.

He went to see a movie with his Iranian friend.

He went on a trip with his Slovak friend.

He is Bulgarian and a very kind person.

He went on a trip with his Belarusian friend.

He is Macedonian and taught me a lot about their culture.

He is Lao, and a very kind person.