Pretty sure its the direct Object.
preposition
In a sentence, the word "action" can function as a noun.
The word down is a noun in that sentence.
A noun.
it depends what word it is it could be any part of speech depending on the sentence
"When" is an adverb when it begins a sentence.
In this sentence, "you" is a pronoun. It is the subject of the sentence and represents the person being addressed or spoken to directly.
The word major is an adjective. The word expect is a verb.
All subjects are part of speech for they are all nouns.
you
a sentence is a part of speech
Pronoun
Noun