I'm pretty sure 'cities' is a plural noun. It is not a possesive noun becuase unless you had another word with it, it can't be possesive alone
Like.... The woman's car.
This sentence has a possessive noun right before the word car.
Car is the direct obeject of the possesive noun.
What kind of car?
The -an article
I don't know for certain of that is accurate.
Look at grammar websites for an even more accurate response
Jargon is a language that belongs to a group , often a profession . so in that case it can be useful for teachers and maybe even a group of people in work so yes.
