What’s an auxiliary verb?

Verbs are also helpful in a number of other ways, which are not so obvious. There are also auxiliary or ‘helping’ verbs that are used in a variety of ways. The main auxiliary verbs are behave and do.

  1. They are used with main verbs to make specific tenses:
    • He is coming. present continuous
    • She wasn’t driving. past continuous
    • We haven’t seen an eclipse before. present perfect
    • She had dropped her keys. past perfect
  2. The verb be + a past participle is also used to make passive forms:
    • The road is mended once a year.
    • The engines are made in Germany.
    • The votes are being counted in the hall.
    • The whales had been driven onto the shore.
  3. The auxiliary verbs are used to make questions:
    • Do you want a drink?
    • Don’t you like opera?
    • Have you finished the work yet?
    • Which train do you think you’ll catch?
  4. Auxiliary verbs are used to make exclamations:
    • Wasn’t she awful!
    • Haven’t you grown!
    • Didn’t they do well!
    • Isn’t it freezing!
  5. To make questions tags:
    • We’re very happy, aren’t we?
    • It’s cold, isn’t it?
    • You don’t like fish, do you?
    • You haven’t had a happy childhood, have you?

Note that the verb to be is the most common verb in English and it is the only one that can operate as both a main verb and an auxiliary verb. It doesn’t need any additional help to make questions or negatives.

  • I am very happy.
  • Am I very happy?
  • I’m not very happy.

Compare this with the verbs do and have which need additional help to make questions and negatives.

  • have a very large nose. I don’t have a very large nose.
  • do my piano practice at 6 o’clock. I don’t do my piano practice.

What’s a modal auxiliary verb?

They are also ‘helping’ verbs because they are used to express a range of meanings, such as certainty, probability, possibility, suggestion, permission, instructions, requests, obligations, necessity, ability and so on. The main modal auxiliary verbs are:

  • can could may might
  • shall should will would
  • must ought to
  • also need to be able to have (got) to

The main types of use

  • certainty / probability (must, will, ought to, can’t, should)
    • He must be feeling very unhappy at the moment.
    • She ought to forget him, and move on.
  • possibility (may, might, could, can)
    • She might arrive on the 5 o’clock train.
    • They may come on Sunday, but I’m not sure.
  • suggestion (may, could, shall, might)
    • Shall we start again?
    • You may want to read over your essay again.
  • permission (may, can, could)
    • Can I connect this wire now?
    • You may begin the examination.
  • instructions and requests (would, will, can, could)
    • Can you explain that words of one syllable?
    • Could you close the door, please?
  • obligations / necessity (must, have to, have got to)
    • must send my mother a card on her birthday.
    • I’ve got to re-write this essay.
  • ability (can, could, be able to)
    • couldn’t stop laughing!
    • He won’t be able to shift that stone.