I'm studying conditional forms, and as I understood most of the time the if clause did not happen, for example in If I had prepared for the interview, I wouldn't be so nervous, so it means that I did not prepare for the interview.

In Summit 2 book there is a note as:

To express inference in conditional sentences, different combinations of tenses can be used:

If you don't know the answer to this question, you didn't do your homework.

My problem is in the meaning, does it mean that you know the answer or not, or it is unknown? Why?

1 Answer 1


No, it is not implying that you do or don't know. To get the "irrealis" case (implying that the antecedent is not true) you need to use a past verb form.


If you don't know the answer, you didn't do your homework.

slightly suggests that you don't know it, but that is because of the pragmatic effect of saying this at all. The words don't have that implication.

If you didn't know the answer, you could ask somebody.

implies that you do know it, and this is talking about an imagined set of circumstances.

  • True, but If you didn't know the answer, you could have asked somebody strongly implies that you don't know it (or at least, didn't at some critical point in the past). Is your final "sentence" an editing artefact? Jan 24, 2016 at 21:55
  • 2
    "My last sentence" was indeed an editing artefact, which I have now removed. I had been going to discuss that very question, but decided it would add complexity without answering the question. The point is that a simple past in the antecedent (except "was") is potentially ambiguous between an irrealis condition in the present and a realis one in the past: this is mainly resolved by the tense or modal form of the consequent.
    – Colin Fine
    Jan 24, 2016 at 22:10

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