Here is a sentence I've read in an article from BBC News:

According to a new book, South Korean Popular Culture and North Korea, South Korea's government "targeted the export of popular media culture as a new economic initiative, one of the major sources of foreign revenue vital for the country's economic survival and advancement".

I don't know if the title of my question would be the case but I would say "one of the major sources of foreign revenue which is/ being vital for..." because vital is an adjective. However, the original sentence sounds absolutely fine to me, maybe because I've come across sentences structured that way. As an English learner, I would be grateful to get clear rules or any document about this grammatical point.

  • You have created an apposition, which is perfectly acceptable. I'll leave you to look that up.
    – Lambie
    Feb 25, 2021 at 18:43

1 Answer 1


That's a reduced relative clause or an adjective phrase, according to this website:
ThoughtCo "Reduced relative clause"

Search it for "adjective phrase", and the instructions "Reduce to an adjective phrase".

  • Thanks for the useful link. However, the use of commas is another confusion. As you can see, there's no comma in my case while there are in all the examples suggested in the document. So is comma necessary or optional in those cases? Another concern is that this type of reduced relative clauses is not offered in common english learner sources (Cambridge, Oxford, etc.) so is it standard english that I can use in speaking or writing test?
    – Thanhgiang
    Mar 26, 2020 at 3:22
  • A comma isn't needed in that example. The usage in your example sentence is very common. Whether you use a comma for a relative clause depends on whether the clause is essential or non-essential (also called restrictive and non-restrictive). By googling, I see that there are some exercises for the two types of clauses which you may want to try. You can also try reducing them according to rules which you can google. I believe the use of commas will stay the same. Mar 26, 2020 at 5:14

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