It seems like English grammar has about a million rules to learn. Between subject-verb agreement, Oxford commas, and active vs. passive voice, it’s easy to get lost in the grammar shuffle. But there aren’t actually a million grammar rules — in fact, if you master just these few, you can avoid common grammar mistakes.
Every sentence needs two parts to be complete.
Depending on the verb, a complete sentence — also known as an independent clause — might also have a direct object (Katie plays the violin). If your sentence is missing a subject or a verb, it’s a sentence fragment.
You may not expect to find disagreement in a sentence about kittens, but the sentence “My kittens wants food” is definitely having an argument with itself. The subject (kittens) is plural, but the verb (wants) is singular.
For subject-verb agreement, match singular subjects to singular verbs and plural subjects to plural verbs.
- My kitten wants food. (singular subject, singular verb)
- My kittens want food. (plural subject, plural verb)
Although writing in simple sentences is grammatically correct, it’s not very interesting. Combine your simple sentences with coordinating conjunctions (for, and, nor, but, or, yet, so) to make compound sentences.
- Delia found a cat, and she named it Purdy.
- Our team won the championship, so we got a trophy.
You can also mix it up by using a semicolon instead of a conjunction.
- Delia found a cat; she named it Purdy.
- Our team won the championship; we got a trophy.
While you can use a comma with a coordinating conjunction, you can’t use a comma alone to combine independent clauses. That’s an error known as a comma splice, and it creates run-on sentences. Use a comma only if you’re also using a coordinating conjunction.
- Delia found a cat, she named it Purdy. (Incorrect - comma splice)
- Our team won the championship, and we got a trophy. (Correct - with coordinating conjunction)
When listing items in a sentence, you separate them with commas. The last comma in the series is called the Oxford comma, and not everyone likes it.
- We bought some goats, cows, and horses for our farm. (Oxford comma)
- We bought some goats, cows and horses for our farm. (No Oxford comma)
Whether you regularly use an Oxford comma is up to you and your style guide. However, you should always use an Oxford comma when the sentence could be confusing without it.
- The farmer saw the goats, Gil, and Pierre. (Oxford comma clarifies that there are goats and two people named Gil and Pierre)
- The farmer saw the goats, Gil and Pierre. (No Oxford comma makes it sound like the goats are named Gil and Pierre)
Sentences in active voice put the subject before the verb. For example, in the active sentence “The duck ate the bread,” the duck is the subject. It performs the action in the verb (ate) to the object in the sentence (the bread).
In these examples, the subjects are bold, the verbs are underlined, and the objects are italicized.
- Shelby dried the dishes. (Active — Shelby is the subject)
- Mary walked the dog. (Active — Mary is the subject)
Passive voice sentences place the subject after the verb — or they leave the subject out completely. “The bread was eaten by the duck” is a passive sentence because the subject (the duck) comes after the verb (was eaten). The object of the sentence (the bread) somehow ends up at the beginning of the sentence, which makes it confusing to read.
- The dishes were dried by Shelby. (Passive — the subject is after the verb)
- The dog was walked by Mary. (Passive - the subject is missing)
Writing in passive voice makes your sentences confusing and your meaning unclear. Luckily, it’s easy to turn passive voice into active voice.
Using a verb tense that doesn’t match your time period is like stepping into a broken time machine. When did the action happen — today, tomorrow, or one hundred years ago? Is it still happening?
Make sure that you’ve got the correct tense for the time period you’re describing.
- Present tense - something that happens all the time, or is happening right now (Mary and I eat lunch every Tuesday.)
- Past tense - something that happened before now (Mary and I ate lunch.)
- Future tense - something that will happen in the future (Mary and I will eat lunch.)
When talking about a continuous action, you can use present, past, or future progressive tense (with -ing verb endings). If you’re talking about something that happened across a span of time, use perfect verb tenses (with the modal verb have or had).
Another part of using the correct verb tense concerns consistency. If you start your sentence (or paragraph, or page, or book) in one tense, you need to make sure the rest of your writing is also in that tense. You can go back and forth if you’re talking about different time periods, but be careful not to mix them up.
- Incorrect - Stuart lost his wallet. He goes to the bank and gets some cash, then he went to the restaurant. (The tense goes from past to present, back to past again)
- Correct - Stuart lost his wallet. He went to the bank and got some cash, then he went to the restaurant. (Tense stays in the past)
- Correct - Stuart loses his wallet. He goes to the bank and gets some cash, then he goes to the restaurant. (Tense stays in the present)
Many people use apostrophes in plural nouns because — well, we’re not sure why. Apostrophes note when letters are missing in a contraction and they indicate a singular or plural noun’s possession. Those are the only jobs of an apostrophe.
- Correct - Xander can’t wait until summer vacation. (can’t is a contraction of cannot)
- Correct - Did you borrow the neighbor’s car? (neighbor’s is a possessive noun)
- Correct - This is the writers' room. (writers’ is a plural possessive noun)
- Incorrect - Merry Christmas from the Henderson’s! (Hendersons is plural, not possessive)
The rare time you’d use an apostrophe to show plurals is for plural lowercase letters (as in “Mind your p’s and q’s”). Otherwise, keep them away from your plural nouns.
Using too when you mean to is a common — and avoidable — mistake. Make sure you know the difference between common homophones to keep your meaning clear.
These aren’t the only commonly confused words in English. Find the ones that confuse you the most and learn how to tell them apart.
All good things must come to an end, and that includes your sentence. Be sure that you’re using the correct end punctuation mark for your sentence for the tone you want.
- Period - Paul asked Sadie to the dance. (Serious or neutral tone)
- Question mark - Paul asked Sadie to the dance? (Confused tone)
- Exclamation point - Paul asked Sadie to the dance! (Excited tone)
If your sentence ends in a quote or dialogue, put your end punctuation (also called terminal punctuation) inside the quotation marks as well.