He was dressed in a white shirt worn buttoned to the throat ...

[Khamala]

He was dressed in a white shirt worn buttoned to the throat and grey, neatly pressed trousers.

I don't understand why 2 V-3 go after shirt? What they mean?

 

[Barque]

2 V-3

I haven't followed this. I'm guessing "V" stands for "verb" but it'd be easier if you wrote out what you mean.

 

[Khamala]

Yes, I mean past participle. In reduced clauses I see only 1 verb, not 2 like this.

 

[Barque]

I'd say "buttoned" is an adverb there.

a white shirt worn buttoned to the throat

...a white shirt [that was] worn [with it being] buttoned to the throat...

"Buttoned to the throat" means all the buttons were done up, including the collar button, the way you would if you were wearing a tie. But he probably didn't have on a tie; he'd just done all the buttons up.

 

[Khamala]

But why we need "wear" while we have "was dressed in"?

 

[Rover_KE]

Khamala, as emsr2d2 asked you in an earlier thread, ' Please provide the source and author of the quote. You must do this in post #1 every time you quote someone else's words'.

Additionally, I've changed your thread title. Titles must contain some or all of the words/phrases you are asking about.

 

[Barque]

But why do we need "wear" when while we have "was dressed in"?

Please note the corrections above. Also, the word isn't "wear"; it's "worn". If you use quotes, that means you're quoting something exactly as it is.

"Dressed in" in that sentence tells you what he was wearing--a white shirt and grey trousers.
"Worn" in that sentence tells you how the shirt was worn--buttoned up to the throat.

Yes, that sentence would work without "worn" too but using it doesn't make it unnatural.