He is an expert in international relations.

In Marxism, it is said that the relations of production form the foundation of society.

By chance, he met my old friend.

In the early morning, he brewed coffee and started his day.

He completed the project in a week.

I'm always busy during the daytime, and I only have time to rest at night.

He had been working overseas for an extended period of time.

The theory of spacetime is an important part of physics.

Mr. Mashiwa is my best friend.

Sakakima is my best friend.