Common Grammar Errors

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Grammar Errors Undermine Your Work

Grammar errors in your work – especially common grammar errors – undermine your credibility, and this can prevent your readers from accepting your message. Put another way, your readers are likely to concentrate on your mistakes rather than what you're saying.

If you're presenting a new idea or something controversial, your assertions could be ignored if your writing contains errors. More specifically, upon noticing the errors, your readers will deduce that they are smarter than you, and so it will be harder for you to convince them, influence them, or take them on your mind journey.

Not all grammar errors are a disaster. Some are, and some aren't. In our list of 70 grammar mistakes, we have ordered them by seriousness as follows:

• Mistakes that will damage your credibility (11 errors)
• Mistakes that will make you look careless (21 errors)
• Mistakes for which you'll be forgiven (21 erros)
• Mistakes most people won't notice (13 errors)
• "Mistakes" that might annoy (7 errors)

A List of Common Grammar Errors

Common grammar errors include mistakes with:

(1) Contractions

• This is engineering at it's best.
• Your welcome.

(2) Homonyms or near homonyms

• This idea will bare fruit.
• Implementing the new system does not effect the budget.

(3) Possessive apostrophes

• Here is a scan of the boys' heart.
• I would like to display the womens' range.

(4) Subject-verb agreement

• A box of tools were needed.
• Neither the CEO nor the MD are available.

Common Grammar Errors Ordered by Seriousness

Some grammar errors are more damaging than others. The list below starts with the bad ones and ends with the ones your readers probably won't notice. (You can use this list to prioritize our lessons and tests.)

Mistakes That Will Damage Your Credibility

Confusing any of the following:

• you're and your
• its and it's
• they're, their and there
• too and to
• allot, a lot, and alot
• then and than
• who's and whose

Writing any of the following:

• a double superlative or comparative
• Jack is more better.
• Jack is better.
• an apostrophe in a plural
• There were two shark's.
• There were two sharks.
• could of, would of, or should of
• I should of known.
• I should've known.
• her's, our's, or their's
• Their's is better than our's.
• Theirs is better than ours.

Mistakes That Will Make You Look Careless

Confusing any of the following:

• affect and effect
• adverse and averse
• bare and bear
• being or been
• fewer and less
• imply and infer
• loose and lose
• past or passed
• principal and principle
• role and roll
• stationary and stationery
• weather, whether and wether
• cite, sight and site
• decent, descent and dissent
• allude and elude
• e.g. and i.e.

Doing any of the following:

• Mixing up colons and semicolons
• Cannibals don't eat clowns: they taste funny.
• Cannibals don't eat clowns; they taste funny.
• Putting a capital letter on a common noun
• Elves are make-believe, just like Vampires and Eskimos.
• Elves are make-believe, just like vampires and Eskimos.
• Using a misplaced modifier
• Smelly and heavy, Janet encouraged the walrus to leave.
• Smelly and heavy, the walrus left after Janet's encouragement.
• Misplacing a possessive apostrophe
• The cat scratched the dogs' nose.
• The cat scratched the dog's nose.
• Failing with subject-verb agreement
• The box of tapes were found under the stairs.
• The box of tapes was found under the stairs.

Mistakes For Which You'll Be Forgiven

Confusing any of the following:

• who and whom
• already or all ready
• breathe and breath
• climactic and climatic
• complement and compliment
• definite and definitive
• dependant and dependent
• discreet and discrete
• disinterested and uninterested
• lay and lie
• lead and led
• licence or license
• loath and loathe
• practice or practise
• appraise and apprise

Doing any of the following:

• Failing to use hyphens in compound adjectives
• The Mustang was a single seat, single engine fighter aircraft.
• The Mustang was a single-seat, single-engine fighter aircraft.
• Using "my wife and I" when you mean "me and my wife"
• It is a present from my wife and I.
• It is a present from my wife and me.
• Starting a sentence with "however"
• I think it is true, however, I am not confident.
• I think it is true. However, I am not confident. (best)
• I think it is true; however, I am not confident. (acceptable)
• Failing to use a comma after a conjunctive adverb (e.g., however, consequently)
• He has arrived. Consequently I should leave.
• He has arrived. Consequently, I should leave.
• Using a comma before "which" or "who" at the wrong time
• I know the man, who rang the bell.
• I know the man who rang the bell.
• Failing to use comma before "which" or "who" when required
• My eldest brother who lives in New York won the lottery.
• My eldest brother, who lives in New York, won the lottery.
• Using "the latter" with a list of more than two
• I caught a perch, a bass, and a pike. The latter was the biggest.
• I caught a perch, a bass, and a pike. The pike was the biggest.

Mistakes Most People Won't Notice

Confusing any of the following:

• enquiry and inquiry
• amount, quantity, and number
• compose and comprise
• economic and economical
• historic and historical
• if and whether
• altogether and all together
• amoral and immoral

Doing any of the following:

• Joining an adverb and an adjective with a hyphen
• He is an extremely-talented actor.
• He is an extremely talented actor.
• Failing to use an apostrophe in a temporal expression
• The printer comes with 3 years insurance.
• The printer comes with 3 years' insurance.
• Using a capital letter for a season
• Tornadoes are most common in the Spring and least common in Winter.
• Tornadoes are most common in the spring and least common in winter.
• Failing to use a comma to show direct address
• Can I introduce you to my sister John?
• Can I introduce you to my sister, John?
• Illogically placing punctuation inside or outside a quotation
• Did she say "I love you?"
• Did she say "I love you"?

"Mistakes" That Might Annoy

These are not mistakes, but lots of people think they are.

Confusing any of the following:

• can and may
• alright or all right

Doing any of the following:

• Ending a sentence in a preposition
• This is the type of situation I get angry about.
• Using a split infinitive
• I want you to really try.
• Starting a sentence with "and" or "but"
• I won three teddy bears on the shooting stall. And I didn't have my glasses.
• Using a comma after an awkward subject
• Those who know, know.
• Treating "none" as a plural word
• None of us know the answer.

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