The coexistence of humans and nature is important for the future of the Earth.

He received a threat letter.

This building needs reinforcement.

My father serves as the president of the mutual aid society.

Bats use echolocation to fly around in the dark.

This is my first time crossing the border.

He continues his journey to find his own utopia.

It's difficult to understand his situation.

He has anthropophobia and avoids contact with people.

He has arachnophobia, and he panics as soon as he sees a spider.