vendy said:
I'm so confused
what does this sentence mean?
"It's sad, isn't it? All these older guys partying way past their
prime."
It means, It's sad (i.e. pathetic), isn't it? that all these guys
are partying way past their prime."
The phrase 'that all these guys are partying past their time' refers to "It" of "
It's sad" (i.e.
That all these guys are partying way past there time is sad, isn't it?). What's sad ~ pathetic is that partying (i.e. drinking, dancing, having fun, etc.) is usually associated with youth. The words 'past their prime' refers to the guys being older than the partying age. The word 'partying' functions as noun, a gerund. The entire phrase 'partying past their prime' modifies 'All these older guys':
Partying past their prime is sad, isn't it?
All these guys are sad, aren't they?
All these guys partying past their prime is sad, isn't it?
We know 'partying past their time' modifies 'All these guys' because we can insert 'who are' between the phrases, like this,
All these guys
who are partying past their time is sad, isn't it?
The phrase 'All these guys partying past their time' functions as the subject, 'is' functions as the verb, and 'sad' functions as the subject complement.
vendy said:
Is it the same case as the sentence "Michael and David disagree about Michael puttting up his posters""?
1. They disagree about
something.
=> They disagree about
the poster.
2. They disagree about
doing something.
=> They disagree about
putting up the poster.
3. They disagree about
someone doing something.
=> They disagree about
Michael putting up the poster.
'Michael' functions as the object of the verb, and that object is modified by 'putting up the poster', an adjectival phrase, headed by a gerund (i.e. a verbal noun).
=>
Michael putting up the posteris what they disagree about.
=>
His putting up the poster is what they disagree about.
=>
About him putting up the poster is what they disagree.
'His' is a possessive pronoun. Pronouns modify
nouns (i.e. His
putting up). The verb 'disagree about' is transitive, so it takes an object. In our example, it takes the noun 'Michael' and the possessive noun phrase (i.e. PossP) 'his putting up'. It doesn't take 'him putting up' because object pronouns do not modify nouns; they replace them.
They disagree about
him putting up the poster.
Note, speakers tend to use 'him' on account of the preposition 'about'. By itself, 'him' is OK,
They don't agree with
him.

(Object of the verb)
When it modifies, however, 'him' changes to 'his', like this,
They don't agree with
his views.
They don't agree about
his putting up the poster.
Note, if 'putting up' were functioning as a verb in this context, then we'd expect to see some form of the verb
BE, like this,
Michael
is putting up the poster.
