Accidentally I've come up with a sentence where the contraction cannot be used, here it is:

*I can't tell you how excited I'm.

Obviously, any other sentence with similar structure (i.e. having a contraction of the verb be at the end of the sentence) falls prey to this as well.

I was wondering if there are other cases where the corresponding contraction (not necessarily of the verb be) cannot be used?

  • 3
    One theory holds that you can't contract away a stressed syllable. I'm not sure that's the whole story, but you can find it discussed at “Is there some rule against ending a sentence with the contraction ‘it’s’?”.
    – Ben Kovitz
    Commented Feb 10, 2015 at 11:07
  • @BenKovitz The rule is quite subtle. ITbasically dictates that an auxiliary can't have a weak form when it is stranded. Only weak forms can contract with pronouns. It is often wrongly said that the auxiliary will then be stressed. This is sometimes incidentally true, but has nothing to do with stranding. We can see this from examples like Who's coming along? - John is! where is cannot contract but is not stressed. Compare that to Is John coming? - He is Where is can't contract but definitely is stressed! Commented Feb 10, 2015 at 14:53
  • @Araucaria I seem to remember you and StoneyB discussing this in another question. Do you remember which question? (I can't seem to find it.) BTW, nice counterexample, "John is," and nice explanation. The "stress" theory just smelled wrong!
    – Ben Kovitz
    Commented Feb 10, 2015 at 14:58
  • @BenKovitz No, I've been trying to track it down too! Commented Feb 10, 2015 at 15:03
  • 2
    user132181, please wait a day or two before accepting an answer. This question may take some time to figure out, and it might attract many good answers (and edits as people improve their answers). For more about why waiting a day or two is generally a good idea, please see “Not so fast! (When should I accept my answer?)”.
    – Ben Kovitz
    Commented Feb 10, 2015 at 15:23

2 Answers 2


When we use an auxiliary verb without any other verbs or complements, we say that that auxiliary verb has been STRANDED. This is usually because we know the listener can userstand what other parts of the verb phrase are missing:

  • Can you open it?
  • Yes, I can! [means "Yes, I can open it"]

Sometimes it is because the complements of the verb have been preposed. This is normally because they are part of a wh- phrase that has moved to the front of the sentence. This is what has happened in the Original Poster's example, where the wh- phrase has moved to the front of the exclamative clause:

  • I can't tell you how excited I am [ this excited.]

When an auxiliary is stranded it must have its strong form. That means it must have a full vowel. Often, but not always, it will be stressed. We can't contract pronouns with auxiliary verbs if the auxiliary has a strong form.

  • Are you listening?
  • *Yes, I'm (X)
  • Yes, I am (grammatical)

Edit note: As noted by Ben Kovitz, the verb have doesn't always seem to have a strong form when stranded after a modal verb: /hi kʊd əv/. I don't know why this is, though. And I've never found anyone who does!

Hope this is helpful!

  • 2
    What verb is missing in the OP's example?
    – Ben Kovitz
    Commented Feb 10, 2015 at 15:08
  • 4
    How about "I could've" (as a complete sentence)?
    – Ben Kovitz
    Commented Feb 10, 2015 at 15:13
  • 2
    I think so. Now I'm still wondering what's going on, but apparently it's a mystery even to linguists.
    – Ben Kovitz
    Commented Feb 10, 2015 at 15:26
  • @BenKovitz I suspect that it's phonetic. "I could've" isn't as different, phonetically, from "I could have" as other contractions. It's pronounced essentially identically to "I could have" when "have" is de-stressed. In other words, we may be writing "I could've" when the speaker may actually be saying "I could have."
    – phoog
    Commented Feb 3, 2016 at 16:24
  • @BenKovitz Does this ELU answer answer your question adequately? I believe it does, because the mandatory stress slot it is talking about can be filled by "could" here, leaving "have" free to be contracted. Commented May 7, 2020 at 13:20

You never want to end a sentence with a contraction unless it's a contracted form of not. Otherwise it sounds like the sentence is unfinished because contractions are often used to shorten auxillary verbs - or it some cases it could sound/look like you are using possessive case.

It is what it's (wrong)

It is what it isn't. (ok)

He told me that he wasn't. (ok)

He told me that he's. (wrong)

Did you talk to him? Yeah, I told him I won't. (ok)

You did this? No, I didn't. (ok)

Who's the winner today? You're. (wrong)

Have you talked to him? I haven't (ok).

You're lying - have you talked to him? I've. (wrong)

Would you do that? I'd. (wrong)

Come on, really, would you do that? You're right, I wouldn't (ok).

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