There is not a single cloud in the sky.

He is very tall.

This building boasts the maximum height in this town.

Highways are convenient for commuting.

He studied for at most one hour.

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.

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

I enjoyed a picnic under the clear sky.