Auxiliary Verb

In English grammar, certain verb forms are classified as auxiliary verbs. Exact definitions of this term vary; an auxiliary verb is generally conceived as one with little semantic meaning of its own, which modifies the meaning of another verb with which it co-occurs. In English, verbs are often classed as auxiliaries on the basis of certain grammatical properties, particularly as regards their syntax – primarily whether they participate in subject–auxiliary inversion, and can be negated by the simple addition of not after them.

Certain auxiliaries have contracted forms, such as -'d and -'ll for had/would and will/shall. There are also many contractions formed from the negations of auxiliary verbs, ending in n't (a reduced form of not). These letter contractions can participate in inversion as a unit (as in Why haven't you done it?, where the uncontracted form would be Why have you not done it?), and thus in a certain sense can be regarded as auxiliary verbs in their own right.

An auxiliary verb is most generally understood as a verb that "helps" another verb by adding grammatical information to it. On this basis, the auxiliary verbs of English may be taken to include:

• forms of the verb do (do, does, did), when used with other verbs to enable the formation of questions, negation, emphasis, etc.;
• forms of the verb have, when used to express perfect aspect;
• forms of the verb be, when used to express progressive aspect or passive voice;
• the modal verbs, used in a variety of meanings, principally relating to modality.

The following are examples of sentences containing the above types of auxiliary verbs:

• Do you want tea? – do is an auxiliary accompanying the verb want, used here to form a question.
• He had given his all. – had is an auxiliary accompanying the past participle given, expressing perfect aspect.
• We are singing. – are is an auxiliary accompanying the present participle singing, expressing progressive aspect.
• It was destroyed. – was is an auxiliary accompanying the past participle destroyed, expressive passive voice.
• He can do it now. – can is a modal auxiliary accompanying the verb do.

However the above understanding of auxiliary verbs is not always strictly adhered to in the literature, particularly in the case of forms of the verb be, which may be called auxiliaries even when they do not accompany another verb. Other approaches to defining auxiliary verbs are described in the following sections.

There is a group of English verbs which have certain special grammatical (syntactic) properties that distinguish them from other verbs. This group consists mainly of verbs that are auxiliaries in the above sense – verbs that add grammatical meaning to other verbs – and thus some authors use the term auxiliary verb, in relation to English, to denote precisely the verbs in this group. However, not all enumerations of English auxiliary verbs correspond exactly to the group of verbs having these grammatical properties. This group of verbs may also be referred to by other names, such as special verbs.

The principal distinguishing properties of verbs in this special group are as follows:

• They can participate in what is called subject–auxiliary inversion, i.e. they can swap places with the subject of the clause, to form questions and for certain other purposes. For example, inversion of subject and verb is possible in the sentence They can sing (becoming Can they sing?); but it is not possible in They like to sing – it is not correct to say Like they to sing? (instead do-support is required: Do they like to sing?).
• They undergo negation by the addition of not after them. For example, one can say They cannot sing, but not They like not to sing (again do-support is required: They don't like...).
• Other distinct features of verbs in this group include their ability to introduce verb phrase ellipsis (I can sing can be shortened to I can in appropriate contexts, whereas I like to sing cannot be shortened to I like), and the positioning of certain adverbs directly after them (compare I can often sing with I often like to sing).

The group of verbs with the above properties consists of:

• the finite indicative forms of the verb be: am, is, are, was, were;
• the finite indicative forms of the verb have: have, has, had, principally when used to make perfect verb forms;
• the finite indicative forms of the verb do: do, does, did, when used to provide do-support;
• the principal modal verbs can, could, may, might, must, shall, should, will, would;
• certain other verbs, sometimes but not always classed as modals: ought; dare and need in certain uses; had in had better; and sometimes used in used to (see the relevant sections of modal verbs for details).

If membership of this syntactic class is considered to be the defining property for auxiliary verbs, it is therefore the above-listed verbs that will be considered as auxiliaries.

Additionally, non-indicative and non-finite forms of the same verbs (when performing the same functions) are usually described as auxiliaries too, even though all or most of the distinctive syntactical properties do not apply to them specifically.

This concerns be (as infinitive, imperative and subjunctive), being and been; and when used in the expression of perfect aspect, have, having and had.

The chief difference between this syntactic definition of auxiliary verb and the functional definition given in the section above is that the syntactic definition includes the verb be even when used simply as a copular verb, in sentences like I am hungry and It was a cat, where it does not accompany any other verb.

Sometimes, non-auxiliary uses of have follow auxiliary syntax, as in Have you any ideas? and I haven't a clue.

Other lexical verbs do not do this in modern English, although they did so formerly, and such uses as I know not... can be found in archaic English.

Lists or sets of auxiliary verbs in English, as given by various authors, generally consist of most or all of the verbs mentioned in the above sections, though with minor discrepancies.

The main differences between the various proposed sets of auxiliary verbs are noted below.

• For the reasons mentioned above, forms of the verb be may or may not be regarded as auxiliaries when used as a copula not accompanying any other verb.
• The verb ought is sometimes excluded from the class of auxiliaries (specifically the modal auxiliaries) on the grounds that, unlike the principal modals, it requires the to-infinitive rather than the bare infinitive.
• The verbs dare and need are not always considered auxiliaries (or modals); their auxiliary-like syntactic behavior (and their modal-like invariance) applies only to some instances of these verbs, e.g., dare and need.
• The verbs had and used in the expressions had better and used to are not always included among the auxiliaries or modals; in the case of used to questions and negations are in any case more frequently formed using do-support than with auxiliary syntax.
• Other verbs with modal-like or auxiliary-like function may sometimes be classed as auxiliaries even though they do not have auxiliary-like syntactic behavior; this may apply to have in the expression have to, meaning must.

As mentioned below, the contractions of negated forms of auxiliary verbs (isn't, shouldn't, etc.) behave in a certain sense as if they were auxiliaries in their own right, in that they can participate as a whole in subject–auxiliary inversion.

Meaning Contribution

Forms of the verbs have and be, used as auxiliaries with a main verb's past participle and present participle respectively, express perfect aspect and progressive aspect. When forms of be are used with the past participle, they express passive voice. It is possible to combine any two or all three of these uses: The room has been being cleaned for the past three hours. Here the auxiliaries has, been and being (each followed by the appropriate participle type) combine to express perfect and progressive aspect and passive voice.

The auxiliary do (does, did) does not necessarily make any meaning contribution, although it can be used to add emphasis to a clause. This is called the emphatic mood in English. An example of this use is found in "I do go to work on time every day." Also, Do does help in the formation of questions, negations, etc.

Other auxiliaries – the modal verbs – contribute meaning chiefly in the form of modality, although some of them (particularly will and sometimes shall) express future time reference. Their uses are detailed at modal verbs article, and tables summarizing their principal meaning contributions can be found in the articles on modal verb and auxiliary verb.

Conditional Sentence

As is typical for many languages, full conditional sentences in English consist of a condition clause or protasis specifying a condition or hypothesis, and a consequence clause or apodosis specifying what follows from that condition. The condition clause is a dependent clause, most commonly headed by the conjunction if, while the consequence is contained in the main clause of the sentence. Either clause may appear first.

Different types of conditional sentences (depending largely on whether they refer to a past, present or future time frame) require the use of particular verb forms (tenses and moods) to express the condition and the consequence. In English language teaching the most common patterns are referred to as first conditional, second conditional and third conditional; there is also a zero conditional and mixed conditional.

Modal Verb

English has the modal verbs can, could, may, might, must, shall, should, will, would, and also (depending on classification adopted) ought (to), dare, need, had (better), used (to). These do not add -s for the third-person singular, and they do not form infinitives or participles; the only inflection they undergo is that to a certain extent could, might, should and would function as preterites (past tenses) of can, may, shall and will respectively.

A modal verb can serve as the finite verb introducing a verb catena, as in "he might have been injured then". These generally express some form of modality (possibility, obligation, etc.), although will and would (and sometimes shall and should) can serve – among their other uses – to express future time reference and conditional mood.

Infinitive

Regarding English, the term infinitive is traditionally applied to the unmarked form of the verb when it forms a non-finite verb, whether or not introduced by the particle to.

Hence sit and to sit, as used in the following sentences, would each be considered an infinitive:

• I can sit here all day.
• I want to sit on the other chair.

The form without to is called the bare infinitive; the form introduced by to is called the full infinitive or to-infinitive.

The other non-finite verb forms in English are the gerund or present participle (the -ing form), and the past participle – these are not considered infinitives.

Moreover, the unmarked form of the verb is not considered an infinitive when it is forms a finite verb: like a present indicative ("I sit every day"), subjunctive ("I suggest that he sit"), or imperative ("Sit down!"). (For some irregular verbs the form of the infinitive coincides additionally with that of the past tense and/or past participle, like in the case of put.)

Certain auxiliary verbs are defective in that they do not have infinitives (or any other non-finite forms).

This applies to the modal verbs (can, must, etc.), as well as certain related auxiliaries like the had of had better and the used of used to. (Periphrases can be employed instead in some cases, like (to) be able to for can, and (to) have to for must.) It also applies to the auxiliary do, like used in questions, negatives and emphasis like described under do-support. Infinitives are negated by simply preceding them with not.

Of course the verb do when forming a main verb can appear in the infinitive. However, the auxiliary verbs have (used to form the perfect) and be (used to form the passive voice and continuous aspect) both commonly appear in the infinitive: "I should have finished by now"; "It's thought to have been a burial site"; "Let him be released"; "I hope to be working tomorrow."

Perfect Infinitive

There are nonfinite constructions that are marked for perfect, progressive or perfect progressive aspect, using the infinitives, participles or gerunds of the appropriate auxiliaries. The meanings are as would be expected for the respective aspects: perfect for prior occurrence, progressive for ongoing occurrence at a particular time. (Passive voice can also be marked in nonfinite constructions – with infinitives, gerunds and present participles – in the expected way: (to) be eaten, being eaten, having been eaten, etc.)

Examples of nonfinite constructions marked for the various aspects are given below.

Bare infinitive:

• You should have left earlier. (perfect infinitive; for similar constructions and their meanings see modal verbs)
• She might be revising. (progressive; refers to an ongoing action at this moment)
• He must have been working hard. (perfect progressive; i.e. I assume he has been working hard)

To-infinitive:

• He is said to have resigned. (perfect infinitive)
• I expect to be sitting here this time tomorrow. (progressive)
• He claims to have been working here for ten weeks. (perfect progressive)

Present participle:

• Having written the letter, she went to bed. (perfect)
• The man having left, we began to talk. (perfect, in a nominative absolute construction)
• Having been standing for several hours, they were beginning to feel tired. (perfect progressive)

Past participle:

• We have been waiting a long time. (progressive, used only as part of a perfect progressive construction)

Gerund:

• My having caught the spider impressed the others. (perfect)
• We are not proud of having been drinking all night. (perfect progressive)

Other aspectual, temporal and modal information can be marked on nonfinite verbs using periphrastic constructions. For example, a "future infinitive" can be constructed using forms such as (to) be going to eat or (to) be about to eat.

Verb

A verb is a word that expresses an action, a state, or an occurrence — and it's the engine of every English sentence. Understanding how verbs work is foundational to everything else in English grammar, from forming questions to building complex sentences.

Verb Forms

Most English verbs have five inflected forms:

• Base form (go, write, climb) — used as an infinitive, imperative, present subjunctive, and present indicative in all persons except third-person singular.
• -s form (goes, writes, climbs) — used for the present tense, third-person singular (she writes).
• Past tense (went, wrote, climbed) — also called the preterite.
• Past participle (gone, written, climbed) — identical to the past tense for regular verbs, but often different for irregular verbs.
• -ing form (going, writing, climbing) — serves as the present participle and gerund.

The verb be is a special case with more forms than any other English verb (am, is, are, was, were, been, being). Modal verbs like can, must, and should have fewer forms than typical verbs.

Main Verbs and Auxiliaries

Verbs in English often appear in combinations: one or more auxiliary verbs paired with a main verb.

• The dog was barking very loudly.
• My hat has been cleaned.
• Jane does not really like us.

The first verb in the combination is the finite verb (it carries tense and agrees with the subject). The rest are nonfinite (infinitives or participles). Notice that these verbs don't always sit next to each other — as in does not really like.

Tense, Aspect, and Mood

English expresses tense (time reference), aspect (how an action unfolds over time), and mood (the speaker's attitude toward the action) mostly through verb combinations rather than word endings. That's why you'll encounter labels like "present progressive" or "conditional perfect" — these are specific tense–aspect–mood combinations built with auxiliaries.

Self-check: If you can change the time of a sentence by swapping one word (She runs → She ran), that word is the verb.

Keep Practising

To build your verb skills from the ground up, try these challenges: Basics. "To be" in Present Tense, Basics. Common Uses of Auxiliary Verbs, and Transitive and Intransitive Verbs.

B1 | Intermediate

B1 is the intermediate level of the Common European Framework of Reference for Languages (CEFR). It marks the point where you move beyond survival English and start expressing yourself with real independence — describing experiences, explaining opinions, and handling everyday situations without a script.

What a B1 user can do

At this level, you're expected to:

• Understand the main points of clear, standard speech and writing on familiar topics — work, school, travel, hobbies.
• Handle most travel situations in English-speaking environments.
• Produce simple connected text on topics you know or care about.
• Describe experiences, events, hopes, and plans, and give brief reasons and explanations for your opinions.
• Communicate in routine tasks that require a straightforward exchange of information.

What B1 grammar looks like

B1 is where grammar starts to get more layered. You're not just forming basic sentences anymore — you're combining ideas, using different tenses with more precision, and starting to handle structures like the passive voice, modal verbs for necessity and possibility, and gerunds vs. infinitives. You're also expected to build complex sentences with linking words and dependent clauses.

Typical B1 grammar areas include:

• Future tenses — distinguishing will, going to, and the present continuous for future plans
• Passive voice — The report was written yesterday.
• Modal verbs — You should apply early. / She might be late.
• Used to — I used to live in Berlin.
• Verb patterns — knowing whether a verb takes a gerund, an infinitive, or both (I enjoy reading vs. I decided to leave)

What B1 doesn't mean

B1 speakers still hesitate, make grammatical errors, and sometimes struggle with less familiar topics. That's normal. The key difference from A2 is that you can keep a conversation going and get your point across even when things aren't perfect. The step up to B2 involves handling more abstract topics, understanding nuance, and producing more complex, accurate language.

Self-check: Can you tell a friend about a recent trip — what happened, what you liked, and what you'd do differently — without switching to your native language? If yes, you're likely operating at B1 or above.

Ready to find out where you stand? Try Are you B1/Intermediate? Test your English CEFR Level to figure out!, then build your skills with challenges like Basics. Passive Voice, Basics. Modal verbs, and Used to.

Difficulty: Hard

Hard difficulty. Difficulty levels represent author's opinion about how hard a question or challenge is.