What does this letter mean?

Old Church Slavonic is the first language written by the Slavs.

Old Church Slavonic is the oldest recorded language of the Slavic group.

This bottle is reusable.

Are you really not going to use this unused laptop?

He is the most competent employee of our company.

Who is the user of this software?

The culture of classical antiquity has a significant impact on the modern world.

The creatures of the ancient times were significantly different from the creatures of today.

The buildings of Ancient Rome still inspire many people today.