They (referring to women or girls) are my best friends.

The Russian Federation has a vast territory.

He has many Russian friends.

He can speak Russian fluently.

He played Russian roulette, risking his life.

He has experienced the harsh winter of fearsome Russia.

The Russian Empire was a nation that existed from 1721 to 1917.

It's better for him not to know the truth. After all, ignorance is bliss.

He is feigning ignorance about that problem.

He knows that pain through his own experience.