I'm having a disagreement with two of my (non-native English speaker) country people about the (un)grammaticality of the following sentences:

  1. I had to tell him at least five times before he actually did it.
  2. I must have told him at least five times before he actually did it.

I'm saying that sentence 1 sounds OK while sentence 2 is odd and ungrammatical. They're saying the opposite.

Could anyone help us here?

(I know must can be used in the past in some circumstances ("he knew he must do it"), but it still strikes me as mostly a present-tense (or present-perfect tense) verb. And as such, I don't think it should be put before a past event. What do you think?)

1 Answer 1


Both sentences are grammatical, but they mean different things. While sentence 1 is sure about the number of times the request was made, your sentence 2 approximates the number of times "I had to tell him" in order to get the same result. The two sentences are not saying the opposite, it is only the degree of certainty that differs.

Must, may, might, can’t and couldn’t are used with a present perfect verb form to show how certain a speaker is that a past situation happened or didn’t happen.

Formula: MODAL + HAVE + PAST PARTICIPLE (to show how certain the speaker is that something happened)

Must have + past participle shows a great deal of certainty that something happened, but there is still some doubt in the speaker’s mind. He/she is not 100% certain. For example:

  • The students did well on the test. They must have studied hard.

(University of Victoria, Canada)

  • Thanks. Isn't "must have" essentially a present-tense form, though? Can "must have told him" really be followed by "before he actually did it"? Aug 22, 2022 at 14:14
  • Yes, it can. It is if you say, I have probably told him at least five times before he actually did it. Must + present perfect (not just have) refers to the past. Present would have been, I must tell him at least five times before he actually does it.
    – fev
    Aug 22, 2022 at 14:38
  • 2
    Modals have no tense. Must have refers to a judgment of likelihood, not necessarily a tense. Don't worry about tenses; much of what is taught to non-native speakers about tenses is nonsense. Look for constructions instead. Aug 22, 2022 at 16:03

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