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Why do we use passive present perfect like in this sentence?

If the bribe were given, it must have been given to officials.

Can't we use passive simple past?

Also, why can't we use past perfect 'had been given' instead of 'have been given'?

  • Why can't we use past perfect 'had been given' instead of 'have been given'? – Rocky May 9 '16 at 7:22
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The verb in your sentence is not the present perfect have been given.

The verb in your sentence is must have been given. You can call it the modal perfect passive.

Here the modal is must; the perfect is indicated by have; and the passive is indicated by been given.

A modal verb such as must (other modals include will, would, shall, can, could, may, ought, and dare) is followed by the bare infinitive. It cannot be followed by a verb that is finite.

The has in the present perfect passive it has been given is a finite verb, conjugated for tense (present), person (third), and number (singular).

The have in the modal perfect passive it must have been given is non-finite, and does not indicate tense, person, or number.

In standard English, the following forms do not occur:

*must had been (given)
*must has been (given)

The modal perfect must have refers to a completed action. Thus a speaker can use it to express 100% certainty about a past occurrence. The same is true for the modal perfect passive must have been.

Thus it must have been given to officials expresses the speaker's certainty that if a bribe was given, the speaker is 100% certain that the bribe was given to officials.

In short, we use must have (active construction) and must have been (passive construction) to talk about our certainty concerning a past action or state. Note that this certainty of the speaker does not have to actually be what happened.

It must have rained.

I'm 100% certain in my belief that it rained.

I thought it must have rained, but it didn't.

I was 100% certain that it rained, but in fact it didn't actually rain.

For more information on modals and how other modals express different amounts of certainty or possibility, see the Modal Tutorial at English Page dot com.

  • So for active I can say that "she didn't give me the address she must have given me" and for passive "she didn't give me the address it must have been given to me by her". – Rocky May 9 '16 at 10:36
  • I am reluctant to call it modal perfect passive as the perfect aspect doesn't go well with an adverb or adverbial phrases such as yesterday as in "it has rained yesterday" which is ungrammatical. But "It must have rained yesterday" is grammatical. It means "must have + past participle" construction indicates the past tense of the modal verb, not the perfect aspect of it. A modal verb can't be followed by finite forms as you mentioned, that's why the past form of the modal verb should be made with "modal + have + past participle". Do you have any reference or link to support your point? – user24743 May 9 '16 at 11:29
  • I also don't agree with "The has in the present perfect passive it has been given is a finite verb". I would not call it a finite verb. – user24743 May 9 '16 at 11:29
  • Then if we say "it must be done soon" then be is not finite form? also if this is not like perfect passive then why we add been like we add in present perfect passive construction i.e "must have been given(by someone) – Rocky May 9 '16 at 15:46
  • @Rocky The be in must be done is not a finite verb, it is the bare infinitive. Infinitives are by definition, non-finite! This includes the to-infinitive and the bare infinitive. – Alan Carmack May 9 '16 at 18:10
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There is a very important rule that you have to follow in English. A "bare infinitive" or "base form of verb" should follow all the modal verbs such as "must". That's why "had" can't follow "must" as it is the past form of to "have".

Now, I am not sure what you mean by "passive simple past", but if you mean "must had been given" by it, it is plainly wrong. It should be "must have been given".

"Must have been given" is not in the present perfect tense. It is in the past tense and it is used when we are very sure about what happened in the past.

You can visit the link to learn more about how it works.

  • What happen when we are not sure about event should we use "would have been given" ? – Rocky May 9 '16 at 9:32
  • @Rocky Try to look up "could have + past participle" and "might have + past participle". – user24743 May 9 '16 at 9:33

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