Is it correct to say:

She speaks so fast that I couldn't understand her.

2 Answers 2


It depends on the context.

  1. Could is used for past and future instances, or sometimes in the present tense (although in the present tense it is normally describing a possibility or is part of a question). For example, She spoke so fast that I could not hear her, or, he could do it if he chooses to. In the present, we use can. If this is in the present tense, the right way to write this sentence is with cannot, or can't.

    She speaks so fast that I cannot understand her.

  2. As John Clifford pointed out, this sentence would be correct if you added the word earlier on the end. It would also be correct if it is common knowledge that you are talking about past events. However, since no time frame is stated for the event, I assumed it was in the present tense.

    I was talking to her yesterday, and I had a tough time. She speaks so fast that I couldn't hear her. Or it could be the following. She speaks so fast that I couldn't hear her earlier.

  • 1
    That's true about the example given, but "could" and "would" are not in general restricted to only past time. They can also be used for present and future time, e.g. could/would you help me move these boxes now? (present); I could/would do it next month if they paid me (future).
    – BillJ
    Feb 9, 2016 at 13:50
  • I would actually disagree with this. Let's say you're talking to person A about person B, a girl you hang out with often who talks fast, about a conversation you had with her yesterday. "She speaks so fast" is a statement about her current speaking speed; you're not saying she spoke fast just on that occasion, but that this is usual for her. "that I couldn't understand her" is saying you couldn't understand her in that conversation because of the fact that she speaks fast. Feb 9, 2016 at 13:53
  • Similar example: "You write so neatly that I had no problems reading your book." Feb 9, 2016 at 13:55
  • @XandarTheZenon That in no way addresses my point that in a conversation where you're stating a current fact about a past event, the OP's sentence works fine. Feb 9, 2016 at 14:22
  • @BillJ I was mistaken when I said that could is past tense, it is also future. But it is not present tense. You said, Could you help me move these boxes now, but that is future tense. You are asking someone to help you do something, so that would be future, since they are obviously not helping you right now. Just because you add now to the end of a sentence doesn't make it present. It just means that you want something done immediately. Feb 9, 2016 at 14:41

Correct is a grey area.

As written, your example sentence communicates one of the following:

  • Tells us simply that the person you're talking about has a tendency to speak quickly (in other words, the dependent clause is used only to emphasize how quickly you think she speaks)
  • Tells us that you have heard her and didn't understand her in the past
  • Tells us that you haven't heard her yet, but you've heard of her; and if you did hear her, you don't think you would be able to understand her

We aren't required to be completely clear and correct in our grammar to be understood by the vast number of speakers.

To be correct, however, you should change the sentence entirely, depending on the truth.

She speaks so quickly that I never can understand her.

I've heard that she speaks so fast that I wouldn't understand her.

The bottom line: Your question is more about the philosophy of grammar than grammar itself. The grammar of the sentence is fine, but the meaning of the sentence is not clear on the surface.

  • It's not about the philosophy of grammar, the questioner simply wants to know if their sentence is grammatically correct. Feb 9, 2016 at 15:37
  • @XandarTheZenon "Correct" in English is a philosophy question to the extent that you need to know what was intended to be conveyed, and whether you want the Prescriptivist answer or the Descriptivist answer.
    – Tim Ward
    Feb 9, 2016 at 16:07

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