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

He looked up at the sky.

I looked up at the sky where the clouds of war were looming.

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.