Which is grammatically correct, and why?

  1. This device does two things: create the whatzit and set the squorple in place.
  2. This device does two things: creates the whatzit and sets the squorple in place.
  • 2
    I wonder if there is one more option: "This device does two things: creating the whatzit, and setting the squorple in place." See this from Google Books: Sourcebook of the Structures and Styles in John 1-10: The Johannine Parallelisms and Chisms
    – herisson
    Feb 11, 2016 at 16:44
  • @sumelic - Yes indeed. +1 for coloring outside the lines! You make a good point.
    – Rob_Ster
    Feb 11, 2016 at 17:53
  • I can concede that the verbs must agree with the singular subject, "device", but am I the only one to whom (2) seems more weird or awkward than (1)? :)
    – Pistos
    Feb 11, 2016 at 19:59

2 Answers 2


The second choice works better, although both have issues.

The sentence begins with a grammatically complete clause, This device does two things." What happens after the colon involves a kind of ellipsis, and in each of the two given options, the omitted word makes all the difference.

In the second (favored) instance, the missing word is it.

This device does two things: it creates the whatzit and sets the squorple in place.

Now the second part of the sentence is a clause, with an explicit subject and a compound verb.

Omitting the it leaves us with a slightly awkward, but unambiguously comprehensible statement.

In the first example, it's hard to tell exactly what might fit in the ellipsis. To is a possibility, as it would turn the verbs from implicit infinitives into explicit infinitives. But how do we construe the infinitives? Are they used as nouns, appositive to "things"? Or could they be used as adverbs of purpose, modifying things? The former seems more likely, but the infinitive sense of the verbs squints, perhaps a greater syntactic sin than the omission of "it."

  • I have to disagree that "this is a type of ellipsis." OP's use of the colon is grammatically correct. (However, I would agree with you if your baseline reasoning is all colons indicate a form of ellipsis.)
    – Stu W
    Feb 11, 2016 at 16:30
  • 1
    The purpose of the colon here is to give illustrative examples of the preceding clause. If you're exemplifying the verb phrase "does ... things", then creates and sets make sense. If you're exemplifying the direct object "things*, then the bare infinitives create and set make sense.
    – deadrat
    Feb 11, 2016 at 17:41


The subject is This device, which is singular.

You can also convince yourself by adding it.

This device does two things: [it] creates the whatzit and sets the squorple in place.

  • 1
    You could also convince yourself by adding to.
    – deadrat
    Feb 11, 2016 at 17:43
  • Intuitively, I'd expect the verbs to match. In this case, present/habitual "does" matching with "creates" and "sets". If "does" were instead "will do", then the matches would be "create" and "set". Or if the phrase were "This device has two purposes:", then the infinitives could be used. Though, I wonder what the answer would be if the initial clause were in the past tense: "This device did two things:".
    – Pistos
    Feb 11, 2016 at 20:03
  • I was just thinking, if instead of the colon OP used an em-dash (or I suppose a comma), then one winds up with creating and setting
    – Stu W
    Feb 11, 2016 at 20:11

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