I try not to play the role of grammar policeman among my family and friends, so I make every effort not to comment on grammatical mistakes when I see or hear them. But I do notice them. When the same mistakes keep appearing from multiple people, I can’t help but wonder why.

Lately, I’ve been seeing and hearing one of the most common errors in the English language – confusing the preposition of with the verb have.

• “I could have walked to work, but I decided to drive instead.”
• “I could of walked to work, but I decided to drive instead.”

It happens all the time. Of and have actually sound alike, especially in informal conversation. However, the mistake should be obvious the moment it is written out. So, why am I still frequently seeing this error?

Coulda/Shoulda/Woulda/Mighta

Could have, should have, would have, and might have are past tense modals, typically followed by a past participle verb which, in the example given above, would be walked.

Part of the problem, of course, is that we normally contract would have, could have, should have, and might have as would’ve, could’ve, should’ve, and might’ve. Native English speakers tend to be lazy at enunciation. What’s more, colloquial speech further alters these contractions to woulda’, coulda’, shoulda’, and mighta’. 65 years ago, Marlon Brando famously uttered the line, “I coulda’ been a contender!” to Rod Steiger in the film On the Waterfront. People have been using this bastardization of the contraction ever since; sometimes intentionally and ironically, but more often they are unaware of doing it.

So, if you write words the way you speak them – a practice called phonetical spelling – you might convince yourself that these past tense modals are written with the preposition rather than the verb. But it’s the verb that reveals the meaning.

Let’s take a closer look at these past tense modals and something called conditionals.

Could Have, or Could’ve

Could have is a past conditional, stating that something was possible in the past, but did not happen.

“I could have gone home after work, but I decided to go out for a drink with my friends.”

“I could’ve had another slice of pie for dessert, but I’m watching my weight.”

Would Have, or Would’ve

Would have takes two forms, depending on your intention. It could be a past unreal conditional, stating that, but for an unknown, there would be different results. The keyword in these phrases is if.

“I would have gone home sooner if I had known that they needed to get up early.”

“I would’ve brought some wine if I knew that she expected us to stay for dinner.”

Would have may also imply choice or regret. The conditional word in these phrases is but.

“I would have taken a sweater, but the forecast was for a warm, sunny day.”

“I would’ve been better off if I had trusted my instincts, but I was reckless.”

Should Have or Should’ve

Should have is a past conditional directly stating regret. It refers to mistakes and is often used in apologies.

“I don’t know why I said that. I should have known better.”

“You should’ve told me that you were working until 10 tonight!”

Might Have or Might’ve

Might have implies that something that was possible in the past did not occur. It is another past unreal conditional. Once again, look for the words if or but.

“I might have a very different career if I hadn’t changed my college major.”

“We might’ve dated sooner, but I was afraid that you thought I was weird.”

Just remember that the verb (to) have is crucial to the sentence. Using the preposition of simply doesn’t make any sense.