His room was empty of air, making it hard to breathe.

The sky is very beautiful, isn't it?

Seeing the empty cup, he poured another cup of tea.

He can recite the poem by heart.

There is not a single cloud in the sky.

The air in this room is fresh.

What will you use this empty box for?

Looking at the bird flying high in the sky, I felt freedom.

The altitude of this airplane is 10,000 meters.

In mathematics, an empty set refers to a set that does not contain any elements.