Auxiliary Verbs

In CGEL, an auxiliary verb is a verb that does not head the lexical predicate, but instead marks grammatical properties of the clause and combines with a non-finite VP.

Most common are: Be, Do, Have. Do and have are also used as lexical verbs

Properties

• Have negative form: do/don’t, does/doesn’t etc. This is not a contraction, but rather an irregular inflected form

• Can stand at the beginning of certain clauses including closed interrogatives.

• The word not can follow auxiliary verb to make the clause negative

Auxiliary Be

• Always auxiliary

• Even if it’s the only verb in a sentence

• Progressive aspect: with gerund-participle: currently in progress, continuing through a period including the present moment, activity that was in progress during some period in the past,

• Predication (copular)

Mary is extremely clever

• Location: PP and Be before it

George is in the kitchen

• Identity: X is Y.

• Roles: Be before an NP naming

Professor Nesbit is dean of the college

• Passive with a past-participle

Do

• Only ever found where auxiliary verb is obligatory

Launch will be ready soon Will launch be ready soon?

But to form a closed interrogative corresponding to a given declarative clause:

They opened on time Did they open on time? Do your homework Did(aux) you do(lex) your homework?

Have

Have(aux) is used when forming a clause talking about a completed past action from a standpoint where it has relevance to the present

The milk went sour (event) The milk has gone sour (similar event, happened in the past, has present relevance)

• Use past participle

• Can be used in the same sentence with Have (lex)

I had had the rash for several weeks

Core points (only what’s relevant here):

Auxiliaries express tense, aspect, modality, or voice

They precede a lexical verb in a non-finite form

They can stand at the beginning of certain clauses including closed interrogatives, but lexical verbs never do

They are able to tune it Can they tune it?

They can tuna ~~Can they tune?~~ (can is lexical here)

The word not can follow an auxiliary to make the clause negative

We have not washed the machine (aux) ~~We have not a washing machine~~

They cannot occur as the sole lexical predicate in the clause (except be as a copular verb, which is a different use)

We were reading the book

We → pronoun, subject

were reading the book → predicate, realised by a VP

were → auxiliary verb (be), marks progressive aspect, selects the non-finite VP reading the book

reading → lexical verb, head of the VP, predicates the event of the subject

the book → object NP, selected by the lexical verb

Predicate: were reading the book (VP, headed by lexical verb reading)

Modals and bare infinitives

• Modals require bare infinitive after them

• So in passive, when using past-participle, insert be

Could leave it out Could be left out (be is the bare infinitive)

In old English modals were full verbs, that took infinitives: Can go, must go. Overtime they lost their inflections and became auxiliaries, but the bare infinitive construction survived

Evidence modals are special auxiliaries:

Property	Example
no to form	✗ to can
no participles	✗ canning (modal sense)
no 3rd-person -s	✗ cans go
inversion without do	Can she go?