Definition of be auxiliary verb from the Oxford Advanced Learner's Dictionary

      

    be

     auxiliary verb
    auxiliary verb
    BrE BrE//bi//
     
    ; NAmE NAmE//bi//
     
    ; BrE strong form BrE//biː//
     
    ; NAmE strong form NAmE//biː//
     
    Verb Forms present simple I / you / we / they am/​are
    BrE BrE//æm//
     
    ; NAmE NAmE//æm//
     
    ; BrE BrE//ɑː(r)//
     
    ; NAmE NAmE//ɑːr//
     
    am not/​are not/​aren't he / she / it is
    BrE BrE//ɪz//
     
    ; NAmE NAmE//ɪz//
     
    is notisn't past simple was
    BrE BrE//wəz//
     
    ; NAmE NAmE//wəz//
     
    ; BrE strong form BrE//wɒz//
     
    ; NAmE strong form NAmE//wʌz//
     
    was notwasn't
    BrE BrE//ˈwɒznt//
     
    ; NAmE NAmE//ˈwʌznt//
     
    past simple were
    BrE BrE//wə(r)//
     
    ; NAmE NAmE//wər//
     
    ; BrE strong form BrE//wɜː(r)//
     
    ; NAmE strong form NAmE//wɜːr//
     
    were notweren't past participle been
    BrE BrE//biːn//
     
    , BrE//bɪn//
     
    ; NAmE NAmE//bɪn//
     
    -ing form being
    BrE BrE//ˈbiːɪŋ//
     
    ; NAmE NAmE//ˈbiːɪŋ//
     
     
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  1. 1  used with a past participle to form the passive He was killed in the war. Where were they made? The house was still being built. You will be told what to do.
  2. 2  used with a present participle to form progressive tenses I am studying Chinese. I'll be seeing him soon. What have you been doing this week? I'm always being criticized.
  3. 3  used to make question tags (= short questions added to the end of statements) You're not hungry, are you? Ben's coming, isn't he? The old theatre was pulled down, wasn't it?
  4. 4  used to avoid repeating the full form of a verb in the passive or a progressive tense Karen wasn't beaten in any of her games, but all the others were. ‘Are you coming with us?’ ‘No, I'm not.’
  5. 5  be to do something used to say what must or should be done I am to call them once I reach the airport. You are to report this to the police. What is to be done about this problem?
  6. 6  be to do something used to say what is arranged to happen They are to be married in June.
  7. 7be to do something used to say what happened later He was to regret that decision for the rest of his life (= he did regret it).
  8. 8be not, never, etc. to be done used to say what could not or did not happen Anna was nowhere to be found (= we could not find her anywhere). He was never to see his wife again (= although he did not know it would be so at the time, he did not see her again). She wanted to write a successful novel, but it was not to be (= it turned out never to happen).
  9. 9if somebody/it were to do something… | were somebody/it to do something… (formal) used to express a condition If we were to offer you more money, would you stay? Were we to offer you more money, would you stay?
  10. Word Origin Old English bēon, an irregular and defective verb, whose full conjugation derives from several originally distinct verbs. The forms am and is are from an Indo-European root shared by Latin sum and est. The forms was and were are from an Indo-European root meaning ‘remain’. The forms be and been are from an Indo-European root shared by Latin fui ‘I was’, fio ‘I become’, and Greek phuein ‘bring forth, cause to grow’. The origin of are is uncertain. Word Origin Old English bēon, an irregular and defective verb, whose full conjugation derives from several originally distinct verbs. The forms am and is are from an Indo-European root shared by Latin sum and est. The forms was and were are from an Indo-European root meaning ‘remain’. The forms be and been are from an Indo-European root shared by Latin fui ‘I was’, fio ‘I become’, and Greek phuein ‘bring forth, cause to grow’. The origin of are is uncertain.
See the Oxford Advanced American Dictionary entry: be