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This is the second time I am seeing something like this. This sentence is written by a native English speaker:

It looks like it's worked. I thought you must of fixed it.

1- It seems wrong to me, please correct me if I am wrong.

2- If it is wrong, why do they use of rather than have?

3- If it is informal language, is it ok to use it in emails, etc...?

marked as duplicate by Em., user178049, Nathan Tuggy, Varun Nair, VictorB Feb 15 '18 at 15:13

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  • 3
    Never, ever, ever, ever use it in emails. It's not an "informally acceptable" way of writing, it's an outright mistake. – tenebris2020 Feb 15 '18 at 12:20

You're not wrong. Quite the opposite, you're absolutely right in thinking that there is a problem with it. You see, phonetically, must've, when you say it fast, sounds very similar to the way you pronounce must of. People just write it as they hear it with no attention at all paid to the rules of orthography. The same thing is also true for things like could've, would've and should've where people commonly misspell them as could of, would of and should of.

And because a lot of native speakers never took the time to study English grammar properly (that's the sad truth), they often make this, I'd say, rather stupid mistake. No offense, but the term dumb would probably be a better word to describe this situation. Though some might disagree, this has really nothing to do with being informal either. That kind of writing style should make any person with at least some basic high-school education or a passing knowledge of English grammar cringe.

  • 2
    "Could of", "would of", "should of", etc are illiteracies. – Michael Harvey Jun 29 at 13:49

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