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What is 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 be, have 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. 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. Auxiliary verbs are used to make question 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.

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

What is 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)
    - I must send my mother a card on her birthday.
    I've got to rewrite this essay.
  • Ability (can, could, be able to)
    - I couldn't stop laughing!
    - He won't be able to shift that stone.


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