He checked his answers against the correct ones.

The moon quietly illuminates the sea.

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.

He made a fake snore to pretend to be asleep.