do: auxiliary verb

The auxiliary verb do is used in a lot of ways.

  • We use do to make questions with ordinary verbs, but not with auxiliary verbs. Compare:
    Do you like I Can you /
  • We use do to make negative sentences with ordinary verbs, but not with auxiliary verbs. Compare:
    I don’t like football.
    I can’t play football.
  • We use do instead of repeating a complete verb or clause.
    She doesn’t like dancing, but I do (= … but I like dancing.)
    Ann thinks there’s something wrong with Bill, and so do I.
    You play bridge, don’t you?
  • We use do in an affirmative clause for emphasis.
    Do sit down. She thinks I don’t iove her. but I do love her.
  • We can use the auxiliary verb do together with the ordinary verb do — so that we have do twice in the same verb phrase.
    What do you do in the evenings?
    ‘My name is Robinson.’ ‘How do you do?