1. Regina is a student.
2. We are teachers.
3. It is a dog.
4. They are police officers.
5. Liza is a dancer.
6. I am hungry but Sally isn't.
7. Hugo is late but I am not.
8. Tigers are dangerous but cats aren't.
9. My friend is at home but I am not.
10. Winter is cold but summer isn't.
The purpose of King's letter is to cause the Church to fight racial injustice.
As you already know, King was a proponent of equal human rights, for both black, and white people. He wanted the Church to be aware of inequalities in the world and fight racism so as to erase those inequalities.
Claustrophobia is the disease when you have a problem with small spaces or people being too close to you, you can also look it up on google.
Formal language I believe that is the right language