I have learnt that past participle phrase can be used non-restrictively, set off by commas, as in 1 and 2, but cannot only present participle phrase be used non-restrictively? If context is clear as in 3, isn't it a sure thing that "threatening people on the streets" modifies "the criminals"?

  1. I will go through the tunnel, located across the street.

  2. Pharmacists utilize a sophisticated computer system, designed to create more streamed lined workflow.

  3. The cctv captured the criminals, threatening people on the street.

  4. The cctv captured the criminals threatening people on the street.

So my questions are

Q1) Like in 1 and 2, can past participle phrase be used non-restrictively? As far as I know, past participle phrase at least can.

Q2) Like in 3, if context is clear enough for people to see "threatening people on the streets" as modifying the criminals, is it grammatically possible to use present participle phrase non-restrictively with commas in order to express the meaning that all the criminals captured on the cctv threatened people on the street? If not, could you give any reason why?

Q3) Is there a difference in meaning between 3 and 4? I think there is, To me, 4 sounds like not all of the criminals, but some of them threatened people on the street, and 3 sounds like all the criminals threatened people because of the comma. This is the main reason why I think of this question as important and am asking on and on.

Q4) Haven't you ever seen any sentences where present participle phrase is used non-restrictively as in 3?

Q5) When is it possible to use present participle phrase non-restrictively? Is it possible only in this case when the phrase can be seen only modifying the subject as in "Students, planning to study nursing, must first meet with the dean" ?

(I'm asking about present participle phrase that is set off by commas and is modifying not the subject, but the its preceding noun, as in example 3)

The point is that I want to know whether it's impossible to use non-restrictively present participle phrase to modify its preceding noun, not the subject in a sentence and if possible, when it's possible or not.

  • 2
    I think you’re asking too many questions in one post. We’d really prefer for you to ask one question per post if possible.
    – user230
    Dec 7, 2019 at 9:24
  • @snailcar I hope so, but I would like to avoid asking similar questions, so I asked like this reluctantly.
    – GKK
    Dec 7, 2019 at 9:27
  • 1
    I'd say that all your examples are restrictive and hence should not be set apart by punctuation.
    – BillJ
    Dec 7, 2019 at 13:51
  • @BillJ then is it wrong to use commas in 1 and 2?
    – GKK
    Sep 18, 2020 at 20:36
  • 1
    In 1. there may be no entailment that there is more than one tunnel: the integrated (restrictive) construction simply provides a succinct way of saying that I will go through the tunnel and the tunnel is located across the street. You could if you prefer use a comma, but in this case there's really no need to.
    – BillJ
    Sep 19, 2020 at 11:05

1 Answer 1


The key here is "if the context is clear". There is no reason why a descriptive phrase can't be restrictive if the situation calls for it.

This means that if there are clearly two tunnels, one of which is "located across the street" and other is "located this side of the street". And you say

I'll go through the tunnel (,) located across the street.

A fluent speaker will not be confused because the comma pause suggests a non-restrictive phrase. There is a tendency for a comma (or a pause and change of intonation) to be associated with non-restrictive phrases, but it is only a tendency and certainly not a strong grammatical rule.

There is another issue in 3, as noted elsewhere the phrase could be understood to be describing the cctv instead of the criminals, though the context would make this an unlikely interpretation. However in

The duck began to swim round the the lake, quacking as she went.

I'd have no difficulty in understanding that the duck was quacking (and not the lake!) This can be called "pragmatic grammar" the same structure can have different meanings depending on the meanings (and not the grammatical function) of the words.

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