AUX: auxiliary verb
AUX covers auxiliaries, that is, function words which characteristically accompany a main predicate
in a clause and help convey information such as tense, aspect, and modality.
In English, there is a class of modal auxiliaries (PTB MD), and there are several non-modal auxiliaries as well
(tagged in PTB as regular verbs: VB, VBP, VBG, VBN, VBD, VBZ). All of these fall under AUX.
Clausal negation words and infinitival marker to are treated separately: see PART.
The list of allowed auxiliaries is registered with the validator. The following lexemes can be modal auxiliaries:
- can, could, may, might, shall, should, will, would, must, ought, need, dare
The following can be non-modal auxiliaries:
- be, have, do, and get (we count passive get as an auxiliary)
The prototypical function of an auxiliary word is modifying the main predicate in an aux, aux:pass, or cop relation.
However, in certain circumstances, a word tagged as AUX may assume the status of the main predicate of a clause (promotion).
Auxiliaries can be coordinated but do not normally take modifiers.
See the syntax overview for details.
Ambiguity with VERB
Note that some lexemes are ambiguous between AUX and VERB.
Both tags are frequent for have and do.
Get, need, and dare are usually tagged VERB, but in rare cases act as auxiliaries:
- The grass got trampled (by the bison). [passive]
- But: I got it fixed. [causative] is VERB
- I have eaten the plums. [perfect]
- But: Now I have to buy some more. is VERB
- Need I say more?
- You needn’t shout.
- But: You (don’t) need to shout. is VERB
Be is almost always an AUX, whether functioning as a copula, or as a progressive or passive marker.
However, we consider be to be a full VERB when, instead of turning a nonverbal item into a predicate,
it resembles the lexical verb exist, most notably in an existential sentence.
- We have been naughty. [copula]
- We are magicians. [copula]
- Magicians are in this act. [copula]
- But: VERB in There are magicians in this act. [existential]
- The grass was trampled (by the bison). [passive]
- We are eating cake. [progressive]
Morphological Features
Non-modal auxiliaries bear inflectional features like ordinary verbs.
At present, modal auxiliaries have VerbForm=Fin as their only feature (though some traditions ascribe them present or past tense).
AUX in other languages: [bej] [bg] [bm] [cs] [cy] [da] [el] [en] [es] [et] [fi] [fro] [fr] [ga] [grc] [gub] [hu] [hy] [it] [ja] [ka] [kk] [kpv] [ky] [myv] [no] [pcm] [pt] [qpm] [ru] [sl] [sv] [tr] [tt] [uk] [u] [urj] [yue] [zh]