He came down the stairs.

I enjoyed a date with him under the cherry blossoms at night.

I saved the draft.

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.

I enjoyed a picnic under the clear sky.

He wants to make a car that can fly in the air.