การใช้

-A (noun) of (noun)
-A (noun) of a (noun)
-A (noun) of the (noun)

-(noun) of (noun)

-The (noun) of (noun)
-The (noun) of a (noun)
-The (noun) of the (noun)

-แต่ละอันควรใช้ตอนไหน เมื่อไหร่?

เช่น

Neoliberalism is everywhere, but at the same time, nowhere. It is held to be [the] dominant and pervasive economic policy agenda [of] our times, [a] powerful and expansive political agenda [of]class domination and exploitation, [the] manifestation [of] ‘capital resurgent’, [an] overarching dystopian zeitgeist [of] late-capitalist excess.​

-the [specific, only] dominant and pervasive economic policy agenda of [belonging to] our times,
-a [one example of a] powerful and expansive political agenda of [belonging to] class domination and exploitation,
-the [specific] manifestation of ‘capital resurgent’,
-an [one example of an] overarching dystopian zeitgeist of [belonging to] late-capitalist excess.

Does that help?

Do not forget
(i) "The" is basically a demonstrative adjective, similar to "that"
(ii) "a/an" is basically an adjective and always has a nuance of "one" or "one from many"
Sociologist

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