Student Stumper 42: Could do vs. Could have done

QUESTION: Which question is correct? “How could I have missed that?” or “How could I miss that?”

ANSWER: If only I could easily and confidently answer that! Could we first look at other uses of this modal verb? We could look at a few examples together if you’d like.

That wasn’t actually my initial reply to the question, but the three previous sentences reveal the first source of confusion over the modal verb could: its different uses. We use it for ability, possibility, requests, suggestions, and offers — and the meaning isn’t always clear, at least immediately. For instance, the words “I could help you” don’t indicate a clear intention without more context. The speaker may be stating a possibility or making an offer. The sentence stress would likely differ, too, depending on the meaning: I could help you. / I could help you.

Even with more context, there can be a gray area between ability and possibility. Imagine a business person speaking to her colleagues: “We could build something special together.” Is she referring to their collective ability or the possibility of building something special?

The forms of could also pose a challenge. We use could with a base verb to refer to the past, present, or future. The perfect form could have (done) is more limited; it helps us speculate about the past or express a missed opportunity, which means someone didn’t use their ability or a possibility wasn’t explored:

  • How does Ken know so much about that period of history? I suppose he could have read books or watched documentaries. [speculation about the past, a past possibility]
  • I could have done better if I had had more time. [a hypothetical reference to past ability]
  • I could have enrolled in the evening course if I had known about it. [a hypothetical reference to past possibility]


  • I could stay up late and get by on little sleep when I was in college. [real past ability]
  • Our university offered us a lot of choices. We could take classes at some of the neighboring colleges. [real past possibility]

To return to the original question, “How could I miss that?” may be used to refer to a past situation in which the speaker acted, but failed to achieve a successful outcome. This isn’t hypothetical. Maybe the speaker failed to attend a party or failed to notice a mistake. We may be in the gray area between ability and possibility, but the situation is clearly a real past event. “How could I miss that?” is very much like, “How could I do such a thing?” I’m asking myself why I did something I shouldn’t have done, not why I didn’t do something I should have. Does that make sense?

A real-life example appears on a PGA golfer’s blog. Darren Golsby wrote a post “How Could I Miss That Putt?” Even professional golfers are not perfect, as he points out. They may putt to the best of their ability, but there’s always the possibility that their ball will miss the hole. The question, “How could I miss that putt?” is a common one, according to Golsby. He equates it with, “I shouldn’t have missed that putt!” Note how should is different. To make a past reference, we need the perfect form shouldn’t have missed.

So when would we use “could(n’t) have missed”? Consider these next examples:

  • I knew I couldn’t have missed the exit.  [a past impossibility with “couldn’t have missed” being placed before “knew” on a timeline]
  • I was surprised to see my high score on the test. I thought I had made some mistakes, but the teacher could have missed them when she was grading it. [a past possibility with “could have missed” being placed before “was surprised” on a timeline]

Questions with the perfect form seem more suitable for speculation. “Could we have missed something?” asks a police detective while reviewing the evidence of an unsolved case. In contrast, any kind of “How could you?” question is likely asked out of surprise at someone’s actions. “How could you do that to me?” asks a friend who was betrayed. “How could I be so stupid?” we ask when we wonder at an unwise choice. In short, the key is to match up forms, uses, and time frames.

Did I miss anything in this explanation? Please fill in any gaps if I did. I’ll follow up with a handout for those who’d like to clarify these points with their upper level students.


Biber D. et al. (2002). Longman student grammar of spoken and written English. Essex: Pearson Education Limited.

Golsby, Darren. (2015). How could I miss that putt? Darren Golsby PGA Professional. Retrieved from


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