Plenty of phrases in English sound awkward but are grammatically correct. Similarly, there are a few phrases that sound right, but aren’t. When we’re speaking, it can be difficult to catch these grammar goofs. It’s much easier to catch these mistakes when writing. Sometimes, the mistake is swapping one word for another — think of “intensive purposes” vs. “intents and purposes.” For other phrases, the perpetrators are much sneakier: prepositions and contractions. Let’s look at one of the most common preposition and contraction mix ups.

Could Have vs. Could Of

“Could” is used to indicate both possibility and willingness. We understand that when someone says they could do something, they’re saying they’re able to do it, and they’re willing to. In a question, it’s also asking about permission to do something.

Because of this flexibility, “could” is a helper verb, otherwise known as an auxiliary verb. It’s paired with a second verb to make the sentence clearer.

Example: I could go to the dance.

Example: I could run to the store.

Now let’s talk about “could of.”

Coulda, woulda, shoulda. This turn of phrase for something you wish you had done differently may sound like “could,” “would,” and “should” are sliding into the preposition “of.” But as we now know, “could” needs a verb, not a preposition, to make a sentence work.

Correct: I could have gone to the store.

Incorrect: I could of gone to the store.

In the incorrect example, “of” isn’t connecting to a noun, pronoun, or phrase, so the sentence doesn't work.

English is full of contractions, in both writing and speech. “Could have,” when used as a contraction, becomes “could’ve,” which is almost indecipherable to the ear from “could of.” When speaking, the meaning is clear, but if you’re writing, make sure to use the correct contraction.

Bonus grammar lesson: “Could have” combines a verb conjugated in the past participle (could) with a present-tense verb (have). It signals to the listener that it’s a past action being referred to in the present.

Other Preposition Mix Ups

There are a few other prepositions that easily get confused in conversation. For two prepositions that seem interchangeable, “in” and “into” function differently in sentences. “In” is best used when referring to a fixed location.

Example: The car is in the garage.

But “into” implies motion, making it much more useful to indicate that you’re moving forward.

Example: I’m going into the concert venue now.

“On accident” vs. “by accident” is another preposition misstep. Or is it? Linguistic researchers found that “on accident” jumped in usage for younger English speakers. “By accident” is more common for older speakers. This may be another instance where colloquial language shifts, so the rules shift along with it.

If you catch yourself making one of these mistakes, don’t worry. That’s how we learn. Are there other prepositions that you always mix up?

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