ACT® · English: Usage Conventions
Frequently Confused Word Pairs
Frequently confused word pairs sound alike or look alike but do different jobs in a sentence. The test checks whether you can swap in a quick test phrase to find which spelling actually fits the slot.
These pairs survive every review session because your ear can't help you. There, their, and they're are pronounced the same way, so the mistake isn't about hearing the sentence wrong, it's about not checking what job the word is doing. The fix is never to sound it out again. It's to run a quick substitution test that only one spelling can survive.
For they're, expand it to 'they are' and read the sentence back. 'The delegates said they are arriving Thursday' works; 'the delegates said there arriving Thursday' doesn't. That single substitution replaces guessing with proof. The same logic works for past versus passed: only passed can act as a verb, so if the sentence needs an action word in that slot, passed wins, no matter how 'past the mark' might sound right. Then versus than splits a different way, by job rather than sound: then marks a moment in a sequence, than sets up a comparison, so 'faster than ever' needs than because faster is doing comparison work.
This topic sits next to subject-verb agreement and pronoun case because all three ask the same underlying question: what grammatical job does this slot need filled, regardless of what sounds natural. Once you're scanning for job rather than sound, lead versus led stops being a trap too, since led is simply the irregular past tense of the verb lead, spelled to avoid colliding with the metal.
Key terms
- Homophone
- A word that sounds identical to another word but has a different spelling and meaning.
- Substitution test
- Replacing a contraction with its full words to check whether the sentence still makes sense.
- Irregular verb
- A verb whose past tense isn't formed by adding -ed, like lead becoming led.
- Comparison word
- A word such as than that sets two things against each other, as opposed to marking time like then.
Watch it explained
- How it worksHow does substituting the long form, 'they are' for 'they're', settle the choice on the spot?
- Worked exampleFind the right word for 'The runner ___ the baton to her teammate' between passed and past.
- Common mistakeWhy isn't 'lead' the past tense of 'lead', when the metal rhymes with 'led'?
- Common mistakeWhy doesn't 'then' belong in 'faster then ever', where a comparison is being drawn?
Check yourself
End of topic.