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5 Common Grammar Mistakes & How to Avoid Them

Learning Apr 15, 2021
Grammar is one of the most frustrating (and thus, most feared) aspects of writing. Check out this list of 5 common mistakes, along with our tips on how to avoid them.
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Grammar is one of the most frustrating (and thus, most feared) aspects of writing. It can feel arcane, unclear, and just a pain in the neck. There are even areas where there’s no clear agreement -- ask a writer if they use a serial comma and you’re sure to spark a heated debate (1)!

I think a large reason why grammar has this reputation is because of the litany of rules, and because there are a lot of easy mistakes that can make or break how well something reads. In the course of my own writing, and reviewing that of others, I’ve run into a lot of various blunders, minor errors, or unclear decisions. But I’ve found that if you are able to avoid a few very common mistakes, it really cuts down on the amount of errors that you have to fix in your work. So, without further ado, here are five very common mistakes that you should keep your eyes open for when writing.

1.“Its” versus “It’s”

This, to me, is the most common mistake that I see that even native speakers can get confused over. While apostrophes are a frequent issue for people, getting “its” vs “it’s” is much more frequent and undiscussed as compared to the next section. To know which one you should use, remember: “it’s” is a contraction of “it is”, while “its” is a possessive referring to something that was already mentioned. I find that almost always, if you expand “it’s” to “it is”, you can tell if you’re using the right one. For example, the sentence “It’s running.” If you expand it, it reads as “It is running” -- a good use of “it’s”. On the other hand, the sentence “It was laying on its side” would sound awkward if it was “it was laying on it is side”, so use “its”.

2. They’re, their, and there

A lot of ink has been spilled on these three words, so I’ll keep this section briefer. What’s important to remember here is this:

  • They’re -- is referring to the state of something: “they are”
  • Their -- is used when a group of people possess or have control of something: “their car”,  like “his car” or “your car” for 3rd and 2nd person.
  • There -- refers to a location: “over there”

The trick I mentioned for “it’s” can help here sometimes, but things you can ask yourself to help make sure it’s the right word include: Is this referring to something a bunch of people own? Is a location involved? Be sure to check exactly what the word is referring to and this will help you avoid any confusion.

3. Unnecessary commas (especially before the word “Because”)

This one can be a bit contentious, because some people feel it’s more of a stylistic decision. There are also a massive amount of errors that can be covered regarding commas. Garner’s Modern American Usage spends about 2 dictionary sized pages on the subject! For the sake of brevity, I’ll focus on one that appears quite frequently: commas before the word because. See the below sentence:

“I ran to the store, because I needed to buy peppers.”

The comma in the example is a mistake and is unnecessary -- it’s not separating anything that needs to be separated. The word “because” serves as a coordinating conjunction and links the two parts together.  This mistake happens a lot because people are told that commas can represent a pause in speaking, but in this instance it doesn’t belong. To avoid this, my suggestion would be to not do it altogether --  it’s extremely rare for it to be considered acceptable and even then it would likely sound better if rephrased.

4. Subject-verb disagreement

I would say this is less common than the others, but I’m including it here because when it does appear in writing, it’s jarring; I would say this error can really derail whatever you were trying to communicate to the reader because of how distracting it is. An example of this error is below:

“The actors is performing a play today.”

The subject, “the actors”, is plural -- however, the verb “is” is singular. This is the crux of the error: the subject and verb aren’t both singular and instead mismatch. There are two ways to avoid this I find useful. The first is making sure you know the subject of your sentence and can match the verb to it. The second is just reading the sentence out loud: a lot of times, a big error can be really noticeable if you hear it being spoken!

5.  Abusing the passive voice

This is an error that happens a lot in academic writing (I had a lot of issues with this myself when I was writing). In writing, there is an “active voice” and a “passive voice”. These refer to two different ways a sentence can be structured:

  • Active voice sentences are where the subject acts upon an object. They are organized as Subject + Verb + Object. For example: He yelled at the waiter.
  • Passive voice sentences, on the other hand, are where the object is acted upon by the subject. They are organized as Object + Verb + Preposition (the word “By”) + Subject. For example: The waiter was yelled at by him.

The passive voice isn’t necessarily incorrect in all circumstances; it’s very useful if you’re trying to emphasize the object of the verb (“My boyfriend was attacked by a dog!” has a different emphasis than “A dog attacked my boyfriend!”, for example). However, overuse of it generally feels as if the writer isn’t confident in what they’re saying, or can just read bizarrely. See if you can tell the difference:

  • War was finally declared by the British in August of 1914.
  • The British finally declared war in August of 1914.

The latter sentence is clearer and sounds more confident. Try to use the active voice whenever possible!

While there are still many things about grammar to remember and watch for, hopefully this list and these tips help you avoid some pitfalls so you have more energy and time for other things in your writing!

(1) Author’s note: please use a serial comma.


Nick Chlumecky

Nick Chlumecky is the head of Operations at QuillBot and helps assist across the business.
He has an M.A. from University of Victoria and in his spare time he enjoys listening to podcasts and napping.

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