I found these two sentences and I want an explanation for them to illustrate why they go like:

  • A number of boys were absent.

Although the subject is singular, but the sentence is considered as plural?

  • three eggs is plenty

And in this example, the writer used is instead of are.

  • 2
    "three eggs" is collective there. Replace it with "It": "It is plenty." Some collective nouns are considered plural; others could be considered both singular and plural. "A number of (noun)" is almost always treated as a plural (exception may be "a number of times is too many times", but this is because it is a collective "It" as the subject). Other ones that can be both are "jury", "group", "class", "crew", "audience", "committee", "staff (of people)", "team", "public", etc. Most collectives can be both, but "police" is always plural; however, "the law" can be both. – Nick Dec 28 '17 at 19:45
  • Incidentally, the "a number of boys were" passage is discussed at length in this related question. Also related: the 50 miles is question. – J.R. Dec 28 '17 at 21:05
  • Does “a dozen schools” act like “a number of boys”? @J.R. – Bavyan Yaldo Dec 29 '17 at 13:28
  • @BavyanY - It depends on how it's used, which is explained quite well in this answer. – J.R. Dec 29 '17 at 15:24
  • @JR This question, namely "'Three eggs is plenty' vs. 'a number of boys were absent,'" is not an exact duplicate of "What is the head in 'a number of boys.'" The cited question is at an entirely different level of sophistication, and the highest ranked answer is appropriate to that sophistication. It may well be useless to the person initiating this thread. We have valued procedure over teaching. I have an entirely different view of the citation in your most recent comment. I would have had no objection had that been the initial citation. So I think we are on the right track now – Jeff Morrow Dec 29 '17 at 16:10