You wouldn't say "I have four of mango", "fours of mangoes" etc.Out of the three, which is the best option and with which grammatical rule:Four dozen (of) mangoes were delivered from the storehouse.But as you can see here, the results are very contrasting to the previous one:English Language Learners Stack Exchange is a question and answer site for speakers of other languages learning English. Dozen is a collective noun, like committee. Collective nouns name groups of people or items. But it does have its own plural form (dozens). Maybe the explanation given by Larry Barkley is more applicable here. “Here is a dozen eggs” sounds fine and correct to me, as does, “Here is a pair of keets for your birdcage.” Likewise, “The committee is reconsidering its numbers”, and, “The committee is divided about its position.” And in all similar cases: the team is, the family is, the group is, the public is, the government is, etc.Thanks for all the constructive criticism.

(as plural only, always followed by of) A large, unspecified number of, comfortably estimated in small multiples of twelve, thus generally implied to be significantly more than ten or twelve, but less than perhaps one or two hundred; many. I’m going to take another run at this one.Totally agree w/Bill, and the example of eggs is exactly what came to mind.

Collective nouns name groups of people or items. It is a … Visit the LanguageTool homepage to use it online or download it for free. If you have "a dozen" then you refer to an amount that includes 12 items - dozen here is regarded to be a -> single group, therefore it's used in singular. In this particular sentence, I would suggest that the noun “dozen” functions as an adjective modifying/describing the plural noun “conjunctions,” that your verb “are” is actually agreeing in number with “conjunctions,” not “dozen.”Dozen is possibly different in some cases because it refers to a specific number, but it is still “a” dozen. All Right ReservedHere are a dozen top aquariums around the country.Here is a dozen top aquariums around the country.Here is a dozen resources for every student.An alternative might be: “The diners are arguing with each other over the bill.” However, this only works if it doesn’t alter the meaning or intent of the context; the preceding example could be focusing either on the couple or on the argument that they’re having. It only takes a minute to sign up.When the nouns of numbers are followed immediately by "of," their plural forms are used.Give me a dozen ['of those' implied].Use of dozen is, of course, an English oddity, but it does compare to the other units OK: So "I have four hundred mangoes" is the same construction.The rule is simple. That is how it was taught to me at Eton, being told it was the queen’s English and all that.The committee has agreed to appropriate money for new sidewalk.

That is why it seems it should be singular. So what happens with sentences #1,#2 and #3. a dozen eggs were used in the recipe. “The staff (or better, the staff members) were in disagreement as to how to handle the money.”On the Google Ngram Viewer, the construction “Here are a dozen” far outnumbers “Here is a dozen,” but the reverse is true in a Web search.Although common, the singular construction “here is a dozen” is unidiomatic when it is followed by what are clearly distinct items.