All verbs are either auxiliary verbs or main verbs. Auxiliary verbs, also called helping verbs, consist of primary verbs (be, have, do) and modal verbs (can, could, may, might, must, shall, will, etc). The most common auxiliary verbs are be, have, do. Each of these has different forms; for example, the verb be/to be has eight different forms: am, is, are, was, were, be, being, and been. Have has these forms: have, has, having, and had, and do has these: do, does, did, and done. Auxiliary verbs combine with other verbs (main verbs) to form tenses, aspect, voice, modality and emphasis. They are usually placed in front of the main verbs, and there can be two or more auxiliary verbs in a sentence. They change the meaning or time of the action as expressed by the verbs: He does sing. / He is singing. / He has sung. Auxiliary verbs can be used as main verbs in a sentence.
All modal verbs are auxiliary verbs but not all auxiliary verbs are modal verbs. They include can, will, might and should: She can sing. / He will go. / They might come. / We should walk. The modal verbs are shown in the following table.
The auxilliary verbs are:
In the examples above, the first verb in each pair (is, has) is the auxiliary verb, while riding and gone are the main verbs. The two verbs in each sentence combined to form a verb tense.
In the first sentence, the auxiliary verb is used with a present participle to form the present continuous tense: is riding. It tells us that the action is still going on, that is Jill is still riding the elephant.
In the second sentence, the auxiliary verb is used with a past participle to form the present perfect tense: has gone. It tells us the action has been completed.
Auxiliary verbs as main verbs
Auxiliary verbs do not always combine with the main verbs to form tenses. The auxiliary verbs be, have, and do can be used independently as main verbs. When used on their own, they are no longer auxiliary verbs.
Auxiliary verbs combine with other verbs to form aspect
Other areas in which the auxiliary verbs are used
Modals or modal verbs are also auxiliary verbs. They are also called modal auxiliary verbs: can, could, will, would, may, might, shall, should, must, ought to, used to. Modal verbs are used to express ability, etc.
(See Lesson 10 for more on modal verbs.)
Auxiliary verbs often come in contracted forms: have is shortened to ‘ve; is/has to ‘s; and had/would/should/could to ‘d.