You've made some very respectable guesses! (I'm convinced that
there are no right answers to this question, by the way!
![Smile [:)]](/emoticons/emotion-1.gif)
)
The
It's or
It is or
It was and the
who are invariable in all versions of this formula.
The controversy revolves around two other factors.
Should the pronoun before
who be in the nominative (
I, you, he, she, we, they) or in the objective (
me, you, him, her, us, them) case?
Should the verb after
who agree only in number or in number
and person with the
antecedent pronoun? (This factor is important only in the cases of
I am and
You are.)
________________
Taking
I am tired as the base sentence, the four cleft versions which are possible are:
It is I who am tired. (Nominative, number, person)
It is I who is tired. (Nominative, number)
It is me who am tired. (Objective, number, person)
It is me who is tired. (Objective, number)
_____________
With
You are tired,
you singular. (Cases conflated.)
It is you who are tired. (Nom/Obj, number, person)
It is you who is tired. (Nom/Obj, number)
_____________
With
You are tired,
you plural, only one version is possible. (Cases conflated and number and person conflated)
It is you who are tired. (Nom/Obj, number/person)
_____________
Two versions are possible with each of the remaining pronouns. (Number and person conflated)
It is [he / she] who is tired. (Nominative, number)
It is [him / her] who is tired. (Objective, number)
It is [we / they] who are tired. (Nominative, number)
It is [us / them] who are tired. (Objective, number)
_____________
My understanding, right or wrong, is that the most formal and academic usage requires the
It is I who am pattern, i.e., nominative case and both number and person agreement. Some people argue that
I who is is fine. I don't think anyone argues in favor of
me who am. My impression is that, informally in conversation,
me who is might be used.
Following the idea that the maximum of agreement is needed for formal, academic use,
... you who are ... is the version to use, whether
you is singular or plural. Likewise,
... [he / she / we / they] who [is / is / are / are]... are the more formal forms.
____________
Where I live, hardly anybody uses the forms shown above very
much. We prefer to express the same meaning with the following
paradigm:
I'm the one who's tired.
You're the one who's tired.
He's/She's the one who's tired.
We're the ones who are tired.
You're the ones who are tired.
They're the ones who are tired.
This topic is very controversial, and others are sure to have their own opinions on it.
CJ