Must of/must have

[VivaLeBeaver]

I read something the other day and the sentence was "I fell down the stairs, it must of knocked me out".

Shouldn't it be must have?

Yes it should.
It's because people pronounce both of and have the same when they say them quickly - then they get confused when writing it down.

Must have. You are right. This drives me mad.

It's the worst crime against the language I know...
I spent all last summer re-writing the reports done by one of my teachers who had put "could of" "should of" and "ought to of" all over the shop.
I delete people from my FB when they do it.

Well do you want to know where I saw it;

Pinned to the wall in an English classroom at the local comp on their open evening as an example of outstanding work. It was the first sentence, I couldn't bring myself to read any further.

I presurme it's the abbreviation 've that causes the confusion.

'Should've' sounds more like 'should of' than 'should have'.

Still unforgivable though.

• Presume that is.

Yup, must have not must of.

And then there's the dreaded "off of"...

Oh, so DS (aged 8) consistently says "should of", "would of" etc.

I keep correcting him, telling him the correct version has "have".

He replies that "that sounds weird, it can't be right". Aargh!!

Any tips on how I can explain the error of his ways to him?

MrsMadWriggle

Why not show him the reason for the "of" sound? When people abbreviate should have and could have they become should've and could've. The 've is what produces the of sound and the confusion.