He ate a slice of bread.

After running up the stairs, he ran out of breath.

Because he is sharp, he can solve problems quickly.

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.