Question

A rule of thumb is that anything copyrighted before 1922 is in the public domain. once in the public domain, a work is free for everyone to use. the current law states that all materials are copyrighted for the life of the author(s) plus 70 years, and then they enter the public domain. what can be concluded from the passage? the public domain is another way to copyright a work. anything published before 1922 is in the public domain. there are no laws regulating the use of the public domain. all copyrighted work eventually enters the public domain. authors can prevent their works from being in the public domain.

Answer 1

I believe the answer is:  All copyrighted work eventually enters the Public Domain.
The main purpose of copyrighting a work is to protect our work from being re-used by other people without our permission.
If the work is not intended for public viewing, there is no need for us to copyright the work.