ACT English idioms are fixed phrases and preposition patterns— "different from," "capable of," "neither…nor"—where only one wording sounds natural to a native ear, even if another looks grammatical on paper. You cannot logic your way through every idiom; exposure and pattern recognition help.
What shows up
Wrong prepositions, wrong verb + preposition pairs, and correlative idiom breaks. These sit alongside grammar rules in ACT English grammar.
High-frequency patterns to know
- different from(not "different than" on the ACT)
- based on, not "based off of"
- between X and Y (two items); among for three or more
- neither…nor and either…or with parallel structure
How to prep
Log every idiom miss from practice and review weekly. Reading standard edited prose (news, textbooks) builds ear training faster than memorizing long lists. For pronoun-heavy idioms, also see pronoun case.
On test day
Read the full sentence aloud in your head. If one choice sounds like something you would never say in formal writing, trust that instinct when grammar rules do not decide alone.
Start practicing
Start with a free diagnostic, then drill your weak spots with 15-question quizzes and track how you're doing across Reading, English, and Math. Compare plans whenever you're ready to go further.
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