TOEFL Grammar: Reference and comparison 10 medium-level rules, each shown with a correct sentence, the mistake learners most often make instead, and the TOEFL tasks where it counts.
Test Ninjas Research · Updated October 1, 2026
Pronouns have to point clearly back to one thing, and comparisons need exactly one comparative marker. An unclear pronoun in particular can leave a sentence looking fine while making the reader stop and work out what you meant, which is costly in a short email or discussion post.
Part of the
TOEFL grammar guide : 120 rules in 12 topics. The cards are original teaching material checked against the linked references; they are not an ETS syllabus.
The rules 1. Pronoun for one thing Use a singular pronoun for a singular nonhuman referent.
Correct The course changed its schedule.
Common trap · incorrect The course changed their schedule.
What goes wrong: the trap uses “their” where the correct sentence has “its”, so it no longer follows the rule.
Matters for: Write an Email · Academic Discussion
Source: Pronouns
2. Pronoun for a plural group Use a plural pronoun for a plural referent.
Correct The students brought their notes.
Common trap · incorrect The students brought its notes.
What goes wrong: the trap uses “its” where the correct sentence has “their”, so it no longer follows the rule.
Matters for: Write an Email · Academic Discussion
Source: Pronouns
3. Clear pronoun reference When two people are possible referents, repeat a name or noun to make the meaning clear.
Correct After Maria spoke to Elena, Maria sent the file.
Common trap · incorrect After Maria spoke to Elena, she sent the file.
What goes wrong: the trap uses “she” where the correct sentence has “Maria”, so it no longer follows the rule.
Matters for: Write an Email · Academic Discussion
Source: Pronouns
4. Single comparative marker Do not combine more with an er comparative form.
Correct The second draft is clearer than the first.
Common trap · incorrect The second draft is more clearer than the first.
What goes wrong: the trap adds “more”, so it no longer follows the rule.
Matters for: Write an Email · Academic Discussion
Source: Comparison: adjectives
5. Single superlative marker Do not combine most with an est superlative form.
Correct This is the shortest route.
Common trap · incorrect This is the most shortest route.
What goes wrong: the trap adds “most”, so it no longer follows the rule.
Matters for: Write an Email · Academic Discussion
Source: Comparison: adjectives
6. Than after a comparative Use than to introduce the item being compared.
Correct The new plan is simpler than the old one.
Common trap · incorrect The new plan is simpler that the old one.
What goes wrong: the trap uses “that” where the correct sentence has “than”, so it no longer follows the rule.
Matters for: Write an Email · Academic Discussion
Source: Comparison: adjectives
7. Fewer with count nouns In formal academic writing, use fewer for a smaller number of countable items.
Correct Fewer students attended the review.
Common trap · incorrect Less students attended the review.
What goes wrong: the trap uses “Less” where the correct sentence has “Fewer”, so it no longer follows the rule.
Matters for: Write an Email · Academic Discussion
Source: Countability: less or fewer
8. Less with noncount nouns Use less for a smaller amount of a noncount substance.
Correct The new method uses less water.
Common trap · incorrect The new method uses fewer water.
What goes wrong: the trap uses “fewer” where the correct sentence has “less”, so it no longer follows the rule.
Matters for: Write an Email · Academic Discussion
Source: Countability: less or fewer
9. Ones for plural substitutes Use ones to stand in for a plural count noun already known.
Correct I need blue folders, not the red ones.
Common trap · incorrect I need blue folders, not the red one.
What goes wrong: the trap uses “one” where the correct sentence has “ones”, so it no longer follows the rule.
Matters for: Write an Email · Academic Discussion
Source: Substitution
10. Enough after an adjective Place enough after an adjective when stating that a quality meets a need.
Correct The room is large enough for us.
Common trap · incorrect The room is enough large for us.
What goes wrong: the trap uses the same words in a different order, so it no longer follows the rule.
Matters for: Write an Email · Academic Discussion
Source: Enough
Previous ← Verb complements and voice Next Advanced clause structure → Other grammar topics
Frequently Asked Questions Which TOEFL tasks test reference and comparison? + No task names grammar topics, but these rules matter most in Write an Email, Academic Discussion. Build a Sentence rewards correct word order and forms directly; in emails, discussion posts and spoken answers, errors here make your meaning harder to follow.
Are these official TOEFL grammar rules? + No. ETS does not publish a grammar syllabus. These are original Test Ninjas teaching cards based on standard English usage, with links to the reference pages each rule was checked against.
How should I practice these rules? + Read the rule, then cover the correct sentence and try to fix the trap yourself. Next, write one new sentence of your own that follows the rule, ideally about a campus or class situation.