Auxiliary verbs

Auxiliary verbs, also called helping verbs, are used with a main verb to create compound verb forms. Auxiliary verbs may be followed by one, two, or even three other verbs. Auxiliary verbs are used in affirmative statements, negative statements, and questions. Here are the English auxiliary verbs:

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This lesson provides general information regarding auxiliary verbs. To learn about an individual auxiliary verb, click on one of the links above.

The verbs BE, DO and HAVE are special because they can be used as auxiliary verbs or as main verbs. Here are examples as main verbs.

subject verb  
I am a student.
She does her homework at night.
Tom has two dogs.

Auxiliary verbs are always placed in front of the main verb. The verbs BE, DO, and HAVE are conjugated for tense and person when they are used as auxiliary verbs. When the auxiliary verb is BE, the main verb takes the form of a present participle or an infinitive.

subject aux.
verb
main
verb
     
I am studying English. present participle
 
Tom and Sue were eating.  
 
The party is to begin at noon.   infinitive
 
They were to call me.

When the auxiliary verb is DO, it is followed by a verb in its base form.

subject aux.
verb
main
verb
 
Tom does* drink coffee.
We did take the train.

*Normally, the verb DO is not used in an affirmative sentence. Sometimes, however, it is used to contradict. See the lesson on DO.

When the auxiliary verb is HAVE, it can be followed by a past participle or an infinitive.

subject aux.
verb
main
verb
   
He has seen the movie. past participle
We had left early
 
I have to leave now. infinitive
They had to buy a new TV.

Modal verbs are never conjugated and they are always followed by a base form of the main verb.

subject auxiliary
modals
main
verb
 
Ideas can change.  
You must wait here.

Some statements use more than one auxiliary verb. Note that the first auxiliary verb is conjugated for tense and person. The following auxiliary verbs take the form of a present participle or a past participle. The main verb takes the form of a present participle or a past participle. Here are examples of sentences constructed with two auxiliary verbs.

subject aux.
verb
aux.
verb
main
verb
 
I am beginning to feel tired.
The wind has been blowing all day.

Here are example sentences constructed with three auxiliary verbs.

subject aux.
verb
aux.
verb
aux.
verb
main
verb
 
We have been waiting to go home.
Tom had been trying to call for hours.

Note that auxiliary verbs are always placed between the subject and the main verb.

In questions, the auxiliary verb is separated from the main verb by the subject.

Yes / No questions
aux.
verb
sub. main
verb
 
Is she studying English?
Does Tom drink coffee?
Has he seen this film?
Will you call me later?

Wh– questions
  aux.
verb
sub. main
verb
When are you leaving?
Where does Tom work?
What has he done?
Who can you call?

Auxiliary verbs are used with the negative adverb not to form negative statements. Note that the adverb not is placed between the auxiliary verb and the main verb.

subject aux.
verb
adv. main
verb
I am not playing.
They did not come.
The plants have not grown.
The oven will not work.

To see a detailed lesson on a specific auxiliary verb, click on a link below.

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