I wonder if there are more other auxiliary verbs in addition to that 23 common verbs.

for example when we say : "I let him go." , can we consider the verb "let" as an auxiliary, just because of that it's followed by a bare infinitive as that 23 auxiliaries do?

in other words is any verb followed by a bare infinitive called an auxiliary? if not, what is the exact definition of an auxiliary verb?

  • 2
    No. The canonical auxiliary verbs are the ones that occur in the VP auxiliary verb chain. That's: modal auxiliaries (can, could, will, would, shall, should, may, might, must); have for the perfect; be for the progressive; and be for the passive. In that order. There are many other verbs that can occur in construction with other verbs, but that doesn't make them auxiliary verbs. Commented Aug 31, 2013 at 22:37

3 Answers 3


In this case, I think the Wikipedia article is pretty good.

Auxiliary Verb

So, no, "let" is not an auxiliary verb by most definitions. It's a much more interesting thing--a ditransitive verb with a verbal object.

  • 1
    And you back up the two grammatical assertions in the last sentence with? Commented Aug 31, 2013 at 21:45
  • 2
    Sorry; that was a bit terse. Okay, first the inversion test for "let". "*Let I him go?" Isn't English, so "let" fails the inversion test. Then try the negation test. "*I let not him go." It fails the negation test too. Ergo, "to let" is not an English auxiliary verb. Carnie's "Syntax: A Generative Introduction" has a nice treatment of this in much more detail than Wikipedia. He also explains theta roles (that is, ditransitive verbs with different types of object.) Commented Sep 1, 2013 at 15:49
  • 1
    Ah, so you meant: 'It's a much more interesting thing... if one accepts the Generative Grammar model, it's a ditransitive verb with a verbal object.' Other treatments would simply label this structure ('I let him go') a complex catenation (S-V-DO-Vnon-f) Commented Sep 1, 2013 at 23:03
  • What's so interesting about ditransitive verbs with verbal objects? ;-)
    – Pitarou
    Commented Feb 3, 2014 at 14:58

I wonder if there are more other auxiliary verbs in addition to that 23 common verbs.

The idea of 23 of them is new to me, but googling provides the following list:

  1. will
  2. shall
  3. can
  4. would
  5. should
  6. could
  7. may
  8. might
  9. must
  10. do
  11. does
  12. did
  13. am
  14. is
  15. are
  16. was
  17. were
  18. be
  19. been
  20. have
  21. has
  22. had
  23. being

That list is incomplete, but arguably also over-long. We can provide a fuller list:

  1. be
  2. am,
  3. are,
  4. is,
  5. was,
  6. were,
  7. being,
  8. been,
  9. can,
  10. could,
  11. dare,
  12. do
  13. does,
  14. did,
  15. have
  16. has,
  17. had,
  18. having,
  19. may,
  20. might,
  21. must,
  22. mote,
  23. need,
  24. ought,
  25. had better,
  26. shall,
  27. should,
  28. will,
  29. would
  30. used to

Not all of them are used much as such in all dialects, and in particular mote is pretty much obsolete bar the expression "so mote it be" found in Freemasonry, Wicca and some other modern magical or religious practices influenced by one or both of those.

We could add on contractions, and have a few more in the list (lots more if we allow the very many different dialect contractions of some of them), but this list of 30 seems a reasonable attempt to fill out the 23.

However, most of those are different forms of the same word, so we could in fact shorten the list to:

  1. be (am, are, is, was, were, being),
  2. can,
  3. could,
  4. dare,
  5. do (does, did),
  6. have (has, had, having),
  7. may,
  8. might,
  9. must,
  10. mote
  11. need,
  12. ought,
  13. had better,
  14. shall,
  15. should,
  16. will,
  17. would
  18. used to

And indeed, there is a relationship between some of those still listed as separate, with e.g. could being the preterite of can even though when used as auxiliaries the preterite works differently with tenses than it does with other verbs. Still, we could still shorten the list further:

  1. be (am, are, is, was, were, being),
  2. can/could,
  3. dare,
  4. do (does, did),
  5. have (has, had, having),
  6. may/might,
  7. must/mote
  8. need,
  9. ought,
  10. had better,
  11. shall/should,
  12. will/would
  13. used to
  • this answer spans over about 100 lines and there isn't even one mention of the word in question in there. Hence -1
    – Emanuel
    Commented Oct 9, 2013 at 10:24
  • @Emanuel what word in question? Surely you aren't taking the example of "let" as making that "the word in question", are you? Even if you are, the fact that the 30 words I list that answer the actual question don't include "let" means that I have address that too, in the negative.
    – Jon Hanna
    Commented Oct 10, 2013 at 22:34

Conventional grammarians say no, but they don't have a good reason for that. They have a narrow definition of modal verbs(the NICE properties) that limit auxiliaries to a small class of two dozen defective modal verbs.

I say yes. Fully inflected verbs can be auxiliaries:


These auxiliaries fully inflect, can have objects/complements, can have adverbials independent of the main verb, and can have auxiliaries themselves.

What's more, 'let' is only an auxiliary. It cannot function as a main/lexical verb.

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