He is studying the history of African Americans.

He drew an equilateral triangle shape.

He became neurasthenic due to long hours of work.

Neurons are responsible for transmitting information in the brain.

This figure is an isosceles trapezoid.

Please calculate the area of this right triangle.

The styloglossus muscle plays a role in raising and pulling the tongue back.

The border patrol is strictly monitoring to prevent illegal immigration.

She is learning the grammar of the present progressive form.

Your existence is a great blessing to me.