Usage of "One Of"

[Ched133]

Hello,

I'm studying on how to use the phrase "one of" and I can't seem to figure out why the text I'm using is saying the following:

"He is one of those persons who always THINKS HE IS right" = incorrect

"He is one of those persons who always THINKS THEY ARE right" = correct

"This is one of the rooms that WAS damaged" = incorrect

"This is one of the rooms that were damanged" = incorrect

I thought "one of the rooms" should be connected by "is" and not "are" because you are talking about one is damanged and not rooms are damaged

I'm really confused......anyone can help me

[Mister Micawber]

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These are correct:

He is one of those persons who always THINK THEY ARE right = Many persons think they are right, and he is one of them.

This is one of the rooms that WERE damaged = Several rooms were damaged,and this is one of them.
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For one right person or one damaged room:

He always thinks he is right.
This is the room that was damaged.
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_________________
Native English teacher at Mister Micawber's

[Ched133]

I guess I've been using this incorrectly all along

I thought "one of those rooms" is a preposition and prepositions never dictate the verb.

e.g.

Chicago is one of the cities that was/were affected by the recent home mortgage crisis.

In this above sentence, i'm actually talking about Chicago being one of the affected cities or many cities were affected by the home crisis and Chicago is one of them

[Mister Micawber]

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Chicago is one of the cities that were affected by the recent home mortgage crisis.

Chicago is one of many affected cities.
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_________________
Native English teacher at Mister Micawber's

[Ched133]

So the subject of this sentence is really CITIES and not Chicago

so "one of something" is not really a prepositional phrase and my question is why?

[Mister Micawber]

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Chicago is one of the cities that were affected by the recent home mortgage crisis.

of = preposition

the cities that were affected by the recent home mortgage crisis = object of preposition

that were affected by the recent home mortgage crisis = adjective clause modifiying cities
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_________________
Native English teacher at Mister Micawber's

[Ched133]

I really appreciate your help

So "who and that" modifies the object of preposition. Who and that are really the keys to determining the verb

Let me try to see if i understand this completely

one of the rooms was damaged due to fire = Only 1 room is damaged

Room A is one of the rooms that were damaged due to fire = many rooms were damaged and room A is one of them

one of the guys on the team is tall = only 1 guy is tall

John is one of the guys on the team who are tall = Everyone is tall and John is one of them

I hope I got this right?

[Mister Micawber]

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You've got it perfectly.
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_________________
Native English teacher at Mister Micawber's