Word Classes

Verbs & Auxiliaries

Two coarse categories that share seven fine tags. The coarse scale asks what job is this verb doing — carrying the meaning, or helping another verb carry it. The fine scale asks what form is it in — base, past, participle, present. The same form can do either job, which is why had is AUX in one sentence and VERB in the next while its tag never changes.

What you’ll learn

Separate the main verb from its auxiliaries on the coarse scale
Read the six VB* tags as forms, and pick the right one from the ending and the subject
Know why be, have and do switch category depending on the sentence
Spot the two forms this model files under another family altogether

Job versus form

The fine tags are named for their form. VBD is a past tense form whether it belongs to painted or was; VBG is the -ing form whether it is the main verb or a modifier. There are six of them, plus MD for the modals, which have no forms at all.

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 mood to it. had been baking is one VERB with two AUX in front of it — and on the fine scale those three words are VBD, VBN, VBG, each a form in its own right.

Two categories, seven tags

VERBVerb

The word that says what happens or what is the case — an action (chased, move) or a state (has, in the sense of owning). Every clause has one, and the syntactic diagrams are built outward from it: it is the ROOT of the dependency tree and the right-hand half of the Reed-Kellogg baseline.

How spaCy decides: the word is a verb form and is not helping another verb. has in Priya has two cats is the whole predicate, 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^DETchildren^NOUNchased^VERBthe^DETballoon^NOUNacross^ADPthe^DETlawn^NOUN.

Priya^PROPNhas^VERBtwo^NUMcats^NOUN.

Snails^NOUNmove^VERBslowly^ADVbut^CCONJnever^ADVstop^VERB.

AUXAuxiliary

A helping verb. English has a small set — the forms of be, have and do, and the modals can, could, will, would, shall, should, may, might, must — and they carry the grammar the main verb cannot carry alone: tense (had baked), aspect (was baking), voice (was written), mood (should call), and the question or negation frame (Did the guests leave?).

How spaCy decides: one of those words, with another verb in the clause for it to help. The one case that catches people out is the linking verb: in Marta is a pilot there is no other verb, and yet is comes back AUX. That is a deliberate Universal Dependencies convention — the copula is treated as a helper to the complement, which is why the tree makes pilot the attr and is the ROOT. Existential there is is the exception, and stays VERB.

The^DETbread^NOUNhad^AUXbeen^AUXbaking^VERBsince^SCONJdawn^NOUN.

Marta^PROPNis^AUXa^DETpilot^NOUN.

Did^AUXthe^DETguests^NOUNleave^VERBearly^ADV?

The seven tags below are shared between the two categories. Each is listed once, under the category it most often belongs to; the examples show it in both jobs where both occur.

VBVerb, base form

The base form — the dictionary form with nothing added. It appears after a modal (will check), after to (to relax), in an imperative (Close the gate), and after let or make (let the kettle cool).

How spaCy 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^UHlet^VBthe^DTkettle^NNcool^VBfirst^RB.

The^DTnurse^NNwill^MDcheck^VByour^PRP$pulse^NN.

Close^VBthe^DTgate^NNbehind^INyou^PRP.

VBDVerb, past tense

The simple past: painted, froze, was. One tag for regular -ed and irregular forms alike. It is the most common verb tag in the corpus, and the one most often shared between the categories — was and had are VBD whether they are the main verb or a helper.

How spaCy 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^DTvolunteers^NNSpainted^VBDthe^DTfence^NNyesterday^NN.

Yesterday^NNthe^DTpipes^NNSfroze^VBDsolid^JJ.

VBGVerb, 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). Penn gives all three one tag; the dependency label is what separates them.

How spaCy decides: the -ing ending, unless the word has settled into use as a plain noun. That is the case to watch — a gerund that is the subject of the sentence comes back NN, not VBG, because the parser reads a noun slot and files the word as a noun. See Gerunds.

The^DTtoddler^NNwas^VBDstacking^VBGwooden^JJblocks^NNS.

The^DTbarking^VBGdog^NNwoke^VBDthe^DTstreet^NN.

Swimming^NNkeeps^VBZmy^PRP$grandmother^NNfit^JJ.

VBNVerb, 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 spaCy decides: a past form after have or be, or one used as a modifier. A participle that has become an ordinary adjective goes the other way — the broken vase is JJ, because broken before a noun reads as a description rather than as an event.

The^DTletter^NNwas^VBDwritten^VBNin^INblue^JJink^NN.

Our^PRP$team^NNhas^VBZfinished^VBNthe^DTreport^NN.

The^DTbroken^JJvase^NNlay^VBDon^INthe^DTfloor^NN.

VBPVerb, non-3rd person singular present

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

How spaCy 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.

I^PRPwater^VBPthe^DTferns^NNSevery^DTmorning^NN.

We^PRPoften^RBwalk^VBPto^INthe^DTharbour^NN.

You^PRPlook^VBPtired^JJthis^DTevening^NN.

VBZVerb, 3rd person singular present

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

How spaCy decides: the -s ending on a verb with a singular subject. Because the same ending makes a plural noun, a word that is both a verb and a noun can be misread — and the parser does misread it when the sentence gives it little else to go on.

My^PRP$cousin^NNcollects^VBZvintage^JJpostcards^NNS.

The^DTshop^NNnever^RBopens^VBZbefore^INnine^CD.

The^DTriver^NNfloods^NNSevery^DTspring^NN.

MDModal

A modal: can, could, will, would, shall, should, may, might, must. Modals have no forms — no -s, no -ing, no participle — and always precede a base-form VB. They add possibility, permission, obligation or future reference to that verb.

How spaCy 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 baseline as part of the predicate rather than on its own line — see Modal Auxiliaries.

You^PRPshould^MDprobably^RBcall^VBthe^DTplumber^NN.

Could^MDyou^PRPpass^VBthe^DTsalt^NN?

The^DTparcel^NNmight^MDarrive^VBtomorrow^NN.

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 mood — 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. Present participle VBG, past participle VBN. The whistling kettle woke us. The broken vase lay on the floor.
See: Participles
Finite form: A form that carries tense and agrees with a subject — VBD, VBP, VBZ. The base form and the participles are non-finite. She sings. — VBZ. They sang. — VBD. They want to sing. — VB, non-finite.
See: Grammar Basics

Practice on a real sentence

Three VBD forms, and they are not all the same category: wondered is the VERB, while was and had are AUX. hurt is a VBN — the past participle after had.

“She wondered whether he was sorry he had hurt her.”

Parts of speech

Give every word its coarse Universal Dependencies category.

Words 0/10Attempts 0Correct 0Time 0:00

Sentence — select a part of speech below, then click the word(s) it applies to

She wondered whether he was sorry he had hurt her.