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Auxiliary verbs - Easy Learning Grammar

An auxiliary verb is a verb that is used together with a main verb to show time and continuity.
  • Be and have are the primary auxiliaries. A primary auxiliary is used to construct compound tenses.
  • Be is used to make present continuous and past continuous tenses
  • I am working.
  • Rob is using the computer.
  • We were all wondering about that.
  • Kevin was teaching in America in 1995.
   and also for the passive. See Be for more on be.
  • These books are sold in supermarkets.
  • Martin was arrested and held overnight.
  • Have is used to make present perfect and past perfect tenses. See Have for more on have.
  • Stephen has finished fixing the car.
  • George and Alice have seen the show already.
  • Amanda had already eaten when we arrived.
  • They had not expected to see us there.
  • Do is the supporting auxiliary. It is used in forming negatives, questions, and emphatic statements. See Do for more on do. See Aspect and Compound tenses for more on simple and compound verb forms.
  • I do not like sausages at all.
  • Do you like prawns?
  • You do like prawns, don’t you?
  • Will, may, might, and the other verbs listed on Modal verbs are the modal auxiliary verbs, usually called simply, modal verbs. A modal verb allows us to talk about actions as possible, doubtful, or necessary.
  • Charlie will go home on Friday.
  • Charlie may go home on Friday.
  • Charlie could go home on Friday.
  • Charlie must go home on Friday.
Auxiliaries can be combined together in a single verb phrase. For example, a verb phrase may consist of a modal + a form of have + a form of be + a form of a main verb.
  • I could have been making a bad mistake by trusting him.
  • Sara will have been living in New Zealand for 2 years next month.
  • You must have been given the wrong number.
The auxiliary verb, or if there is more than one of them, the first auxiliary verb, performs these following grammatical functions:
  • It shows tense and is the finite part of the verb phrase.
  • I have seen it.
  • She had seen it.
  • She has been thinking.
  • She had been thinking.
  • It shows number and person agreement with the subject.
  • She has seen it.
  • They have seen it.
  • I am looking for it.
  • You are looking for it.
  • It will take any negative immediately after it.
  • I do not want to do that.
  • She has not been concentrating.
  • It can come before the subject to make a question.
  • Do you want to help us?
  • Have you got a mobile phone?

Contracted forms

Auxiliaries are very often used in contracted forms. In the case of be and have, the contracted form can involve linking the subject and the auxiliary verb into a single form e.g. I’m, I’ve, we’d, Sue’s (Sue has or Sue is).
  • We’re back!
  • (We are back!)
  • I’ve found it.
  • (I have found it.)
  • They’d gone when I got there.
  • (They had gone when I got there.)
  • Tom’s here.
  • (Tom is here.)
The contracted negative form auxiliary + n’t is common with all the auxiliaries except am, e.g. hasn’t, wouldn’t, don’t.
  • She isn’t (is not) trying.
  • We don’t (do not) live here.
  • He hasn’t (has not) seen it.
  • I can’t (cannot) come.
In standard British English, the contracted form of am not, when it is part of a question, is aren’t I.
  • Aren’t I going to need some matches?
  • I’m getting a lift with you, aren’t I?
  • Contracted forms are more informal than full forms. They are therefore more common in spoken English. Full forms are usually preferred in formal written English.
Auxiliaries are used in sentence tags. See Sentence tags for more about sentence tags.
  • You had only just bought that carpet when the kitchen flooded, hadn’t you?
  • It’s Katie’s birthday on Saturday, isn’t it?
  • You are joking, aren’t you?
Auxiliaries are also used to make a short addition to a statement, such as:
  • a positive addition to a positive statement, accompanied by so or too.
  • I went to the park and Lucy did too.
  • I loved the film, and so did Finlay.
  • a negative addition to a negative statement, accompanied by neither or nor.
  • My dad never eats mussels and neither do I.
  • I don’t want to speak to William now. – Nor do I.
  • I can’t understand it. – Neither can I.
  • Auxiliaries can be used in positive sentences to give emphasis. When they are emphatic they are never contracted.
  • You have made a mess!
  • That was a nice surprise!
  • I am proud of Katie. She’s so clever.
In the present simple tense and the past simple tenses the appropriate form of do is used to show emphasis.
  • I do like Penny. – So do I.
  • We did have a lovely time.
An auxiliary on its own can be used to give a short answer to a question. Whatever auxiliary is used in the question is used on its own in the answer. The main verb is not repeated. Short answers are very common in spoken English.
  • Do you like avocados? Yes, I do. or No, I don’t.
  • Have you read anything by Michael Morpurgo? Yes, I have.

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