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Auxiliary verb

Auxiliary verbs are sometimes called helping verbs - they help the main verb that follows.

English auxiliary verbs have the following classes of function: Passive, Progressive, Perfective, Modal, and Dummy.

Table of contents
1 English Auxiliary Classes
2 Properties
3 Other Languages
4 Reference

English Auxiliary Classes


The verb be is used in the passive form to express an action where the subject is unknowable, not known, or of less interest than the action itself, e.g. the window is broken. (See also Grammatical voice.)


This form, also known as the continuous form, uses the verb be. It is used to express the speaker's interpretation of the temporal nature of the event, e.g. I am doing my homework. (See also Grammatical aspect.)


The verb have is used in the perfective form to look back, i.e. retrospectively, at a past action from the present time. Or in other words, it is used to express an action that still has relevance to the present, e.g. Peter has fallen in love. (See also Grammatical aspect.)


There are nine modal verbs: can/could, may/might, shall/should, will/would and must. They differ from the other auxiliaries both in that they are defective verbs, and in that they can never function as main verbs. They express the speaker's (or listener's) judgement or opinion at the moment of speaking.

Some schools of thought consider could to represent the past tense of can. However, according to Michael Lewis, (The English Verb), this is not always true. "Could I get you something?", clearly is not expressing Past Time. Lewis instead suggests that could is a remote form of can. It is evident after re-examining the usage of could in this light, that remoteness does describe the general meaning, e.g.

The remaining modal auxiliaries can be viewed in this same manner. Lewis covers this area in detail in his book, see reference.


The verb do is used to form questions, when the corresponding positive statement does not contain an auxiliary, e.g.



Auxiliaries take not (or n't) to form the negative, e.g. can't, won't, shouldn't, etc.


Auxiliaries invert to form questions:


Auxiliaries can be used for emphasis:

I do like this beer!


Auxiliaries can appear alone where a main verb has been omitted, but is understood:

John never sings, but Mary does [sing].

Other Languages

Some languages use "be" for the perfective forms of some or all verbs, instead of "have" (in Esperanto, for example, Mi estis irinta = I was having-gone = I had gone). French and German use it for verbs of motion and becoming, and (in German) for "to be" itself, as does Italian. The use of auxiliaries is one variation among Romance languages. Finnish uses ole for all verbs: "Sillä niin on Jumala maailmaa rakastanut" (Because so much is God the world loved). English uses "be" only with "go" in some senses.


The English Verb 'An exploration of Structure and Meaning', Michael Lewis. Langauage Teaching Publications. ISBN 0 906717 40 X