Auxiliary verbs, also known as helping verbs, are used along with main or lexical verbs to form complex tenses and to indicate possibility, necessity and permission. They are usually divided into primary auxiliaries (be, have and do) and modal auxiliaries, (such as shall, will, can, may, etc):
- I am [auxiliary verb] coming [main verb].
- I have [auxiliary verb] told [main verb] him.
- She may [auxiliary verb] not come [main verb].
- You must [auxiliary verb] not do [main verb] that.
Some auxiliary verbs have special short forms:
- I am — I’m
- we will — we’ll
- they have — they’ve
- she will not — she won’t
Auxiliary verbs are used in the formation of tenses, questions and negative sentences, and have a number of other important uses in English grammar.