He is an expert in international relations.

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

In this right triangle, since one angle is 30 degrees, its complementary angle is 60 degrees.

The opposite angles of a quadrangle intersect each other.

The wildebeest is a very rare animal.

Mr. Kakuma is my best friend.

Anyway, we need to contact her.

The angle of view of this lens is wide.

The eagle owl is a nocturnal bird, and its large eyes help it see in the dark.

He is learning calligraphy with a square brush.