Learn English – Number agreement of “a thing of the past”


Is the pluralization correct in the following sentences?

  1. To Do lists are a thing of the past.
  2. To Do lists are things of the past.
  3. A To Do list is a thing of the past.

Are they all (grammatically) correct? Which of the three is the best English? Why?

Best Answer

As I believe your intuition says, "are things of the past" is much more common than "are a thing of the past". Consider the Google Ngram below:

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And looking at the actual citations, a reasonable fraction (at least a quarter of them) are grammatical constructions parallel to "to-do lists are things of the past".

However, Google still finds many, many examples parallel to "to-do lists are a thing of the past". These are grammatically correct because in the construction A is/are B, English makes no requirement that A and B have the same number; the requirement is that the verb agrees with A. For a different example, I think that native English speakers would be more likely to say "to-do lists are a problem" than "to-do lists are problems". You can use Ngrams to check that this is currently true (it's changed from 50 years ago) if you replace to-do lists with men, women, or people.