These two sentences are both valid

I write this sentence.

I do write this sentence.

Are these both valid?

I am writing this sentence.

I do be writing this sentence.

  • The last is wrong.
    – Luke_0
    Commented Aug 16, 2012 at 19:10
  • Robert Williams might say it do be... yo.
    – n00b
    Commented Aug 16, 2012 at 19:16
  • 3
    Do be a good fellow, won't you?
    – Robusto
    Commented Aug 16, 2012 at 19:23
  • "I do be writing this sentence" sounds like pirate grammar. However, I searched the full text of Treasure Island and it doesn't seem to be used there. Commented Aug 16, 2012 at 19:46
  • 5
    "To be is to do" - Socrates "To do is to be" - Sartre "Do be do be do" - Sinatra
    – MetaEd
    Commented Aug 17, 2012 at 5:33

5 Answers 5


The rule of Do-Support applies to every main verb in English, except auxiliary verbs.

Do-Support is the process that provides the dummy auxiliary do to carry the tense and swap with the subject in Yes/No- and Wh-Questions

  • Do you still love her?
  • What do you love about her?

tag questions

  • You still love her, don't you?

and negations

  • You don't love her any more.

However, there are two important qualifications for this rule:

  1. The verb be is always treated as an auxiliary verb, even if it's the only verb in its clause. I.e, it can never invoke Do-Support. Which is the answer to the OP's question.
    Other isomorphs of do can occur with be, however:

    • Do be a "Doo Bee", and don't be a "Dont Bee". - Emphatic do, active noun predicates.
    • What I'm gonna do is be her bodyguard. - Active do, active noun predicate.
  2. The verb have, in its sense of "possess", may be treated

    • either as an auxiliary verb, i.e, commuting with the subject: Have you the time?
      (marked as "British" in American English)
    • or as a main verb, i.e, allowing Do-Support:
      Do you have the time? (by far the more common choice in N. America)
  • 3
    Oh, by the way, do is not a modal verb; it's just a dummy auxiliary verb, the same way It in It's easy to tell is a dummy pronoun; they're both put in as markers by the syntax and have no meaning. Commented Aug 16, 2012 at 23:52
  • 1
    +1 May I suggest, however, that you add your comment to the answer? It is germane to the issue at hand and not simply a comment on it.
    – Robusto
    Commented Aug 17, 2012 at 0:25
  • 1
    My point is that people don't always read comment chains. You are, of course, free to do as you like.
    – Robusto
    Commented Aug 17, 2012 at 15:10
  • 2
    @JohnLawler Right, so negative imperative constructions with BE invoke Do-support for the same reason that other constructions do. There is an auxiliary requirement in the construction which can't be met by another verb. However, this example is different from others because BE is still an auxiliary verb. It just can't perform the required function Is that right? (this is my last comment I promise!) Commented Jul 19, 2014 at 16:57
  • 1
    Just a few comments: 1) the correct context for do-support are negation, inversion (not just questions) and VP-ellipsis (not just tag-questions). 2) some speakers do allow do+be in irrealis context (e.g., “why don’t we be a low-tax country instead” - we should be vs. “why aren’t we a low tax country instead” - we in fact aren’t). 3) imperatives take do with be irrespective of emphasis (“don’t be an idiot” is far more common than “be not an idiot”). 4) the answer ignors dialects where do-support is more comprehensive, notably AAVE.
    – Richard Z
    Commented Feb 22, 2019 at 18:01

"I do be (something, something)....." is used regularly in everyday speech in South-East Ireland, where I grew up, but it is not regarded well, and a sign of being from a very specific type of rural, working class background. Its used in this context as a continuous present: "I do be always listening to that radio show on my way home from work"

  • Interesting! It's also perfectly acceptable in AAVE, but as an emphatic. "I don't think you be studying much based on your grades", "But I do be studying all the time!" Commented Sep 19, 2014 at 18:02

What the second of the first pair is doing is adding emphasis. Because we normally use the auxiliary verb "do" in interrogative and negative sentences, not positive sentences.

Question: Do you like apples?

Positive sentence: You like apples.

Negative sentence: You don't like apples.

However, "do" is used in a positive sentence to add emphasis.


I do believe in fairies, I do! I DO!

If my guess is right and you're trying to duplicate the act of emphasizing in the second pair, then it should be done this way:

First pair:

I write this sentence.

I do write this sentence.

Second pair:

I am writing this sentence.

I am writing this sentence.

As you can see, there is no need to add another auxiliary verb in the second pair because the word "be" or "am" is already one.


Do is not usually used as a modal verb. Other answers have explained this and discussed the non-modal use of do with the verb be.

However, do is used as a modal verb to indicate continuous aspect, in some dialects English, as shown in Do be doing be’s: habitual aspect in Irish English.

Thus the strict answer to the question of whether the modal do can be used with the verb be is:

Yes, when do is a modal verb it can be used with the verb be.


All except the last are grammatical, but the second would be found only infrequently. In some regional dialects the construction illustrated by I be writing this sentence is also found.

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