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Word Classes

Verbs & Auxiliaries

A verb’s coarse category names its job: VERB carries the meaning, and AUX is a helping verb. Its fine tag names its form: base, past, participle or present. So has is VERB in Priya has two cats but AUX in Our team has finished the report, and VBZ in both.

What you’ll learn

  • Tell the main verb (VERB) from its helpers (AUX) on the coarse scale
  • Choose among VB, VBD, VBG, VBN, VBP and VBZ from the verb's ending, its subject and the word before it
  • Explain why have and do are VERB in one sentence and AUX in another, while be is almost always AUX
  • Recognise the verb forms the parser tags as a noun (NN) or an adjective (JJ)
  • Avoid four common verb mistakes, such as “You should to rest” for “You should rest”

Job versus form

The fine tags are named for the form. VBD is the past form, whether the word is a main verb (painted) or a helper (was baking). VBG is the -ing form, whether it is the main verb or a modifier. There are six of these tags, plus MD for the modals, which never change their form.

The coarse categories are named for the job. A VERB is the verb the clause is about; an AUX is a helper that adds tense, aspect, voice or modality to it. Read each verb word of The bread had been baking since dawn twice, once for its job and once for its form:

  • baking carries the meaning, so it is the VERB. It is the -ing form, VBG.
  • been helps it, so it is an AUX. It is the past participle, VBN, because it follows had.
  • had helps too, so it is an AUX. It is the past tense, VBD, and it carries the tense of the whole verb phrase.

Two categories, seven tags

VERB Verb

The word that says what happens or what is the case: an action (chased, move) or a state (has, in the sense of owning). Most clauses have one. It is usually the ROOT of the dependency tree, and it sits on the base line of a Reed-Kellogg diagram, after the subject. A clause whose only verb is be usually has no VERB at all (see Auxiliary).

How the parser decides: the word is a verb form and is not helping another verb. In Priya has two cats, has is the only verb, so it is VERB. In Our team has finished the report, it only marks the perfect, so it is AUX. Same word, same tag (VBZ), different category.

The (DET)children (NOUN)chased (VERB, ringed)the (DET)balloon (NOUN)across (ADP)the (DET)lawn (NOUN).

Priya (PROPN)has (VERB, ringed)two (NUM)cats (NOUN).

Snails (NOUN)move (VERB, ringed)slowly (ADV)but (CCONJ)never (ADV)stop (VERB, ringed).

AUX Auxiliary

A helping verb. English has a small set: the forms of be, have and do, and the nine modals (can, could, will, would, shall, should, may, might, must). They carry what the main verb cannot carry alone:

How the parser decides: one of those words, with another verb in the clause for it to help. The verb be is the exception: it is AUX even when it is the only verb, as in Marta is a pilot and The keys are on the table. It is a VERB mainly in there is and there are (existential there), and sometimes in a subjunctive such as that he be present.

This category (AUX) follows the Universal Dependencies convention, which counts be as a helper. The dependency tree does not follow it: the tree still makes is the ROOT and pilot its attr (see cop).

Every word in AUX

  • be, in nearly every use (the exceptions are just above): am, is, are, was, were, be, been, being, and ’m, ’re, ’s
  • have and do, when they help another verb: have, has, had, having, ’ve, ’s, ’d; do, does, did
  • Modals (MD): can, could, will, would, shall, should, may, might, must, ought, the short forms ’ll and ’d, and the ca, wo, sha of can’t, won’t, shan’t
  • need and dare, before a verb with no to: You needn’t worry, I dare not ask
  • get and become, when they form a passive: He got fired, The news became known (see auxpass)
  • Not AUX: have and do as the only verb (has two cats, did the dishes) are VERB. The to of an infinitive and the negator not are PART.

The (DET)bread (NOUN)had (AUX, ringed)been (AUX, ringed)baking (VERB)since (ADP)dawn (NOUN).

Marta (PROPN)is (AUX, ringed)a (DET)pilot (NOUN).

Did (AUX, ringed)the (DET)guests (NOUN)leave (VERB)early (ADV)?

I (PRON)dare (AUX, ringed)not (PART)ask (VERB).

The seven verb tags

The tags name forms, not jobs, so six of them can mark a VERB or an AUX. Only MD is always AUX. To choose a tag, ask these questions in order:

  1. Is it a modal?

    can, could, will, would, shall, should, may, might, must and ought are MD, and so are their short forms (the full list is under MD).

  2. Does it end in -ing?

    Then it is VBG: was stacking, the barking dog.

  3. Is it a past form?

    This includes irregular forms such as froze, written and been. After a form of have or be, or when it describes a noun, it is the past participle, VBN: has finished, was written, the stolen bike. Otherwise it is the past tense, VBD: painted, froze, was.

  4. Does it follow a modal, to, or a form of do?

    Then it is the base form, VB: will check, to relax, Did the guests leave? The main verb of a command and the verb after let or make are VB too.

  5. Otherwise, it is a present form

    With he, she, it or a singular noun it ends in -s and is VBZ: collects, is. With any other subject it is VBP: I water, they are.

Four cases break these rules. The entries below show the first three.

  • A gerund subject is often NN.
  • A participle before a noun can be JJ.
  • A subjunctive base form is VBP after he, she or it, and often VB otherwise.
  • The Do of a command such as Don’t shout is VBP too.

VB Verb, base form

The base form: the dictionary form with nothing added. It appears in five places:

  • after a modal: will check
  • after to: to relax
  • after do, does or did: Did the guests leave?
  • in an imperative: Close the gate
  • after let or make and an object: let the kettle cool

How the parser decides: an uninflected verb form that is not a present tense with a subject. The difference from VBP is entirely about that subject: I water is VBP, will water is VB. The spelling is identical, so this is a decision about the words around it.

Please (UH)let (VB, ringed)the (DT)kettle (NN)cool (VB, ringed)first (RB).

The (DT)nurse (NN)will (MD)check (VB, ringed)your (PRP$)pulse (NN).

Close (VB, ringed)the (DT)gate (NN)behind (IN)you (PRP).

VBD Verb, past tense

The past tense form, which alone makes the simple past: painted, froze, was. Regular -ed forms and irregular forms get the same tag. Helpers have past forms too: was and had are VBD whether they are the main verb or a helper.

How the parser decides: a past form that is not preceded by a form of have or be. Preceded by one it is a participle instead (VBN), which for a regular verb is spelled exactly the same — painted is VBD alone and VBN after has.

The (DT)volunteers (NNS)painted (VBD, ringed)the (DT)fence (NN)yesterday (NN).

Yesterday (NN)the (DT)pipes (NNS)froze (VBD, ringed)solid (JJ).

VBG Verb, gerund or present participle

The -ing form, whether it is a present participle in a progressive (was stacking), a participle modifying a noun (the barking dog) or a gerund (enjoys swimming). All three jobs get the same tag; only the dependency label tells them apart.

How the parser decides: by the -ing ending, in all three jobs. The main exception is a gerund used alone as the subject: the parser often tags it NN, like an ordinary noun (see the note below).

The (DT)toddler (NN)was (VBD)stacking (VBG, ringed)wooden (JJ)blocks (NNS).

The (DT)barking (VBG, ringed)dog (NN)woke (VBD)the (DT)street (NN).

Swimming (NN, ringed)keeps (VBZ)my (PRP$)grandmother (NN)fit (JJ).

VBN Verb, past participle

The past participle: the form used after have for the perfect (has finished) and after be for the passive (was written). For irregular verbs it has its own spelling (written, frozen); for regular verbs it is the -ed form again, and only the auxiliary in front tells it apart from VBD.

How the parser decides: a past form after have or be, or one used as a modifier. Before a noun, some participles are tagged as adjectives instead: the broken vase is JJ, because broken describes the vase rather than an event. Others stay VBN, as in The stolen bike was found.

The (DT)letter (NN)was (VBD)written (VBN, ringed)in (IN)blue (JJ)ink (NN).

Our (PRP$)team (NN)has (VBZ)finished (VBN, ringed)the (DT)report (NN).

The (DT)broken (JJ, ringed)vase (NN)lay (VBD)on (IN)the (DT)floor (NN).

VBP Verb, non-3rd person singular present

The present tense for every subject except third-person singular: I water, we walk, you look, they are. Its name, “non-3rd person singular present”, is its definition: the present form without the -s.

How the parser decides: a base-looking form with a subject that is not third-person singular. This is the tag that separates I water the ferns (VBP) from the water (NN), and the sentence has to supply the evidence. One surprise: after he or she, a subjunctive base form is VBP, as wear is in The rules require that he wear a helmet.

I (PRP)water (VBP, ringed)the (DT)ferns (NNS)every (DT)morning (NN).

We (PRP)often (RB)walk (VBP, ringed)to (IN)the (DT)harbour (NN).

You (PRP)look (VBP, ringed)tired (JJ)this (DT)evening (NN).

VBZ Verb, 3rd person singular present

The third-person singular present — the -s form of the present tense: collects, opens, is, has, does. This is the form that agrees with he, she, it and any singular noun.

How the parser decides: the -s ending on a verb with a singular subject. The same ending also makes a plural noun. So a word that can be a verb or a noun is sometimes misread, especially when the sentence has few other clues.

My (PRP$)cousin (NN)collects (VBZ, ringed)vintage (JJ)postcards (NNS).

The (DT)shop (NN)never (RB)opens (VBZ, ringed)before (IN)nine (CD).

The (DT)river (NN)floods (NNS, ringed)every (DT)spring (NN).

MD Modal

A modal: can, could, will, would, shall, should, may, might, must, ought. Modals do not change their form: they have no -s, no -ing and no participle. They always come before a base-form VB (ought with to in between), and they add possibility, permission, obligation or future reference to that verb.

How the parser decides: a closed list, and the one tag on this page that maps to a single coarse category: every MD is AUX. In a Reed-Kellogg diagram the modal sits on the base line as part of the predicate rather than on its own line — see Modal Auxiliaries.

Every word tagged MD

  • can, could, will, would, shall, should, may, might, must
  • ought, the one modal followed by to: You ought to rest
  • The short forms ’ll (will) and ’d (would): We’ll see, I’d stay
  • ca, wo, sha: the first halves of can’t, won’t, shan’t, which the parser splits into two words
  • Not MD: need and dare are helpers (AUX) but keep their verb tags, VBP or VB. The ’d of She’d left is had, so it is VBD.

You (PRP)should (MD, ringed)probably (RB)call (VB)the (DT)plumber (NN).

Could (MD, ringed)you (PRP)pass (VB)the (DT)salt (NN)?

The (DT)parcel (NN)might (MD, ringed)arrive (VB)tomorrow (NN).

The short and split forms are modals too:

They (PRP)wo (MD, ringed)n't (RB)come (VB).

We (PRP)'ll (MD, ringed)see (VB).

You (PRP)ought (MD, ringed)to (TO)rest (VB).

Common mistakes with verbs and auxiliaries

Four mistakes that many learners make, especially Spanish speakers:

  • No to after a modal. Write You should rest today, not You should to rest today. A modal (MD) takes the base form (VB) with no to, even where Spanish has an infinitive: Deberías descansar hoy. See also common mistakes with modals.
  • One past form is enough. Write Did the bus stop here?, not Did the bus stopped here? The helper did already carries the past (VBD), so the main verb stays in the base form (VB). See the past tense.
  • Keep the -s after he, she, it or a singular noun. Write My cousin collects vintage postcards, not My cousin collect vintage postcards. The -s form is VBZ; without it the verb is VBP, the form for I, you, we and they.
  • Do not add be to the simple present. Write I agree with Diego, not I am agree with Diego (from Estoy de acuerdo). The word agree is already a verb, and be helps a verb only in its -ing form or its past participle: is baking, was written.

Quick check

  1. Look at the two has words in Omar has a guitar, and he has played it for years. Which is a VERB and which is an AUX? What fine tag does each one get?
    Answer
    The first has is the VERB: it is the only verb in its clause, and it means owns. The second has is an AUX: it helps played (VBN, the past participle) make the present perfect. Both are VBZ, the -s form of the present, because the fine tag records the form and the coarse category records the job.
  2. Give the fine tag of each verb in Camila does not drive, so she has bought a scooter.
    Answer
    The two helpers are VBZ: does and has are -s forms of the present, with the singular subjects Camila and she. After does, the main verb takes the base form, so drive is VB. After has, bought is the past participle, VBN. The past tense has the same spelling, as in She bought a scooter (VBD), so only the helper in front decides.
  3. Look at the two is words in Nina is a pianist, and she is practising tonight. What coarse category does each one get? Which word is the VERB?
    Answer
    Both are AUX. The second is helps practising, the VERB, make the present progressive. The first is helps no other verb: it only links Nina to pianist. The parser still tags be AUX when it is the only verb, so the first clause has no VERB at all. The only VERB in the sentence is practising.
  4. A classmate writes: Did you saw my brother? He work at the bakery. Correct the two mistakes, and give the fine tag of each corrected verb.
    Answer
    Did you see my brother? He works at the bakery. The helper Did already carries the past (VBD), so the main verb stays in the base form: see is VB. With he, the present needs the -s form: works is VBZ.

Key terms

Main verb
The verb that carries the clause’s meaning. VERB on the coarse scale, whatever its form. She has a car. — has is the main verb. She has finished. — now it is finished.

See: Subjects & Verbs

Auxiliary
A helper that supplies tense, aspect, voice or modality — forms of be, have, do, and the modals. AUX on the coarse scale. She has finished. The road was flooded.

See: Modal Auxiliaries

Copula (linking verb)
be joining a subject to a description — Marta is a pilot. Tagged AUX by this model even though it is the only verb present. The soup is cold. Marta is a pilot.

See: Subjective Complements

Participle
A verb form that can also modify a noun. The present participle is VBG. The past participle is usually VBN, but one used as an ordinary adjective before its noun is often tagged JJ. The sleeping baby smiled. A lost dog followed us home.

See: Participles

Finite form
A form that can head a clause on its own: VBD, VBP and VBZ, which carry tense and agree with a subject, and MD, the modals. The participles are non-finite, and so is the base form, except in a command or a base-form subjunctive. She sings. — VBZ. They sang. — VBD. They want to sing. — VB, non-finite.

See: Grammar Basics · Mood

Practice on a real sentence

Look for three VBD words with different jobs: the main verb, a helper, and a form of be that helps no other verb. Remember that the parser still tags that be AUX. Then look at hurt: its base, past and participle are spelled the same, so the word in front of it decides its tag.

Loading the practice sentence…