The problem of illiteracy is a serious social issue around the world.

He makes a living as a person who sells items.

This photo has a shallow depth of field, so the background is blurry.

He had a dagger in his hand.

The cerebral cortex is an important part that controls thinking and emotions.

This problem requires solving a nonlinear equation.

It is difficult to solve this nonlinear equation.

This equation has nonlinear characteristics.

He drew a rhombus on the blackboard.

The taiga bean goose is a bird often seen in Japan during winter.