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30 Common Errors & Confusing Words

Grammar is an important part to master in order to improve your TOEFL score.

Remember, Preparation is the key to succeed at TOEFL.

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1. A While vs. Awhile

A while is a noun phrase consisting of a and while, whereas awhile is an adverb meaning “for a while.” A while usually follows the preposition for or in, whereas if you cannot put “for a while” into a sentence, you need to use a while.

  • He went to the store for a while. (if you replace a while with for a while, it does not make sense -> He went to the store for for a while.)
  • You should sleep awhile. (if you replace awhile with for a while, it makes sense -> You should sleep for a while.)

2. Advice vs. Advise

Advice is a noun, whereas advise is a verb.

  • She took my advice and took out a loan.
  • I advised her to take out a loan.

3. Alot vs. A Lot vs. Allot

First of all, the “word” alot does not exist! A lot is frequently misspelled as one word, alot, but it is actually two words.

Memory tip: Think of a lot as meaning, I want a whole lot full of something. (a lot meaning a parking lot, a large area)

The word allot is a verb meaning to distribute.

  • I have allotted this money to the charity.

4. Among vs. Between

Among is used to express a loose relationship of several items. Between expresses the relationship of one item to another item.

  • I found a pen hidden among the papers on the desk.
  • I found a pen hidden between two sheets of paper on the desk.

5. Apostrophes

Compare the following phrases:

  • The girls are at home.
  • The girl’s home.
  • The girls’ home.

The meaning in the above phrases is changed dramatically based on the placement, if any, of the apostrophe. When talking about more than one person or object, there is no apostrophe.

  • chairs (more than one chair)
  • boys (more than one boy)
  • suitcases (more than one suitcase)

The apostrophe with an s is added to show possession.

  • The girl’s home. (the home belonging to the girl)
  • The student’s notebook. (the notebook belonging to the student)

Likewise, an apostrophe is added after a plural word to show possession of that plural noun.

  • The girls’ home. (the home belonging to more than one girl)
  • The students’ notebook. (one notebook belonging to more than one student)
  • The students’ notebooks. (more than one notebook belonging to more than one student)

6. Assure vs. Ensure vs. Insure

Assure means “to tell someone that something will definitely happen.” Ensure means “to make sure of something.” Insure means “to buy an insurance policy.”

  • She assured me that the house would not flood.
  • She took steps to ensure that the house did not flood.
  • She is glad the house was insured against flood damage.

7. Breathe vs. Breath

Breathe is a verb, and breath is the noun form of breathe.

  • It seems that he breathed his last breath.

This also applies to the verb bathe and the noun bath.

8. Capital vs. Capitol

Capital can mean either an uppercase letter, the seat of the government, or money. Capitol is the actual building where the government sits.

  • I would like to visit the Capitol in the capital of the United States, Washington, D.C.

9. Complement vs. Compliment

A complement completes something else, whereas a compliment is something nice you say to someone.

  • His black suit was a nice complement to his black shoes.
  • She complimented him on his shoes.

10. Effect vs. Affect

This one is straightforward–effect is a noun, and affect is a verb!

Memory tip for affect: A is for action, and verbs are about action. Affect is a verb, and it starts with A.

Memory tip for effect: Think of the phrase “cause and effect.” “Cause” ends with an E, and a cause leads to an effect!

11. Emigrate vs. Immigrate

Emigrate means “to move away from a city or country,” whereas immigrate means “to move into a country from somewhere else.”

  • My father emigrated from Venezuela.
  • My mother immigrated to the United States.

12. Except vs. Accept

Except is a preposition that means “excluding,” and accept is a verb meaning “to receive.”

  • I don’t like any of my gifts, except this one. (there is only one gift that I like)
  • Why did I accept all of these gifts?

13. Further vs. Farther

Use farther for physical distance, and further for metaphorical distance.

  • How much farther do I need to drive?
  • I would like to advance further in my career.

14. Good vs. Well

The word good is an adjective, whereas the word well is an adverb.

  • How are you today? I am doing well.
  • I feel good today.

15. Historic vs. Historical

Historic means “famous,” whereas historical means “related to history.

  • What a historic snowstorm!
  • She decided to wear a historical costume for the Renaissance fair.

16. “I feel bad”

Isn’t feel a verb, so shouldn’t the word after it be an adverb, badly? The answer is, NO! Feel is a linking verb, linking the subject to the adjective that describes it. Therefore, the word after feel should, in fact, be an adjective. I feel bad is the correct sentence.

  • The cake smells delicious. (smells is a linking verb; delicious is an adjective)
  • Their talking is loud. (Is is a linking verb; loud is an adjective)

17. I.e. vs. E.g.

I.e. and e.g. are both abbreviations of Latin terms.

E.g. is used to introduce a few examples, whereas i.e. is used to mean “in other words.”

  • After work, I’d like to check out the new supermarket, i.e., Key Food.
  • After work, I’d like to go to a supermarket, e.g., Key Food or Waldbaum’s.

18. Into vs. In To

Into is a preposition showing what something is inside. In and to are two words that just happen to be next to each other on occasion.

  • He got into the train. (into is one unit – a preposition)
  • I dropped in to see you. (drop in is one unit on its own, and to see is another unit)
  • Log in to the website by pressing this button. (log in is a phrasal verb)
  • What is your login? (login is a noun)

The rules above apply to onto and on to as well.

19. Less vs. Fewer

Fewer is for count nouns, and less is for mass nouns. Check out our Count Nouns & Mass Nouns study sheet if you forget the difference!

20. Lie vs. Lay

Compare these two sentences:

  • You lie down on the sofa.
  • You lay the book down on the table.

The second one has a direct object (book), whereas the first sentence does not.


  • Last week, you lay down on the couch.
  • Last week, you laid the book on the table.
  • You have lain on the couch for a few hours.
  • You have laid the book on the table.
lie lay lain
lay laid laid

It just so happens that the past tense of the verb to lie is the same as the present tense of the verb to lay. You just have to memorize it!

21. Loose vs. Lose

Loose is an adjective, and lose is a verb.

  • This shirt is too loose on me.
  • How did you lose your phone?!

22. Numbers

In English, numbers greater than one thousand and up to ten thousand can be written in two ways:

  • 1000
  • 1,000

Numbers above ten thousand can be written by using a comma in the following way:

  • 10,000
  • 247,533

Decimals and money amounts can be written by using a period in the following way:

  • 7.24 = seven and twenty-four hundredths
  • 2.14 = two and fourteen hundredths
  • $1.37 = one dollar and thirty-seven cents
  • $359.08 = three hundred fifty-nine dollars and eight cents

23. Parallel Structure

One of the most common errors in English is disrespecting parallel structure.

Here is an example:

  • I like hiking, swimming, and biking.
  • I like hiking, to swim, and biking.

The second sentence disrespects parallel structure. Parallel structure means using the same pattern of words in a sentence.

  • I was asked to write my report quickly, thoroughly, and accurately.
  • I was asked to write my report quickly, thoroughly, and in an accurate manner.

24. Principal vs. Principle

When principal is a noun, it refers to a person in charge of an organization; when it is an adjective, it means “most important.” A principle is a firmly held belief.

  • What did the principal want to speak to you about?
  • The principal reason she wanted to see me was to discuss my recent tuition payment.
  • It’s not that I don’t have the money, it’s just a matter of principle.

25. Stationary vs. Stationery

Stationary means “not moving,” whereas stationery refers to paper and writing materials.

  • Of course the door will remain stationary if you don’t push it the right way!
  • I love this stationery you printed your resume on!

26. Subject-Verb Agreement with Collective Nouns

If the sentence shows more individuality, you would use a plural verb; however, if the noun is acting as a unit, use a singular verb.

  • The team is heading for practice.
  • The team are eating with their families.

With a prepositional phrase, use a verb tense that corresponds to the subject.

  • Nearly one in four people is Muslim. (one is the subject, so we use a singular verb, is)
  • 25% of people are Muslim. (fractions and percentages can be singular or plural depending on the prepositional phrase that follows; people is plural, so we use are)

27. The “Bacon and Eggs” Rule

When we have two nouns that are used so often together we think of them as a singular idea, we use a singular verb.

  • Bacon and eggs was served at brunch.
  • Macaroni and cheese is delicious.

Likewise, we use a singular verb when we talk about amounts or quantities.

  • A thousand dollars is a lot of money.
  • Ten miles is too far to walk.

Expressions with “one of” are followed by a singular verb.

  • One of my students is a gymnast.
  • One of my friends is going to Africa this summer.

28. Title Capitalization

Here are some basic rules about how to capitalize titles:

  • Always capitalize the first and last word.
  • Capitalize nouns, pronouns, verbs, adjectives, and adverbs.
  • Do NOT capitalize articles, prepositions (shorter than five letters), or coordinating conjunctions.

Here are some examples:

  • A Year in Paris
  • Pride and Prejudice
  • Cheaper by the Dozen

Of course, for every rule there are exceptions, so it is best to look it up if you are unsure of something.

29. Who vs. Which vs. That

Who refers to people, whereas which and that refer to groups or objects. That introduces an essential clause (which adds vital information to the sentence), whereas which introduces a nonessential clause (which adds supplementary, unnecessary information).

  • She is the one who drove me home yesterday. (who refers to a person)
  • I do not like cereal that has chocolate in it. (we do not know what type of cereal without the essential clause)
  • This cereal, which has chocolate in it, is not good for you. (we do not need the information in the nonessential clause)

30. Who vs. Whom

Who refers to the subject of the sentence, whereas whom refers to the object of a verb or preposition.

  • Who wants the last piece of pie? (who is the subject)
  • Whom do you trust more? (you is the subject; whom is the object)

If you’re unsure, try substituting who with he/she and whom with him/her to see if they fit.

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