Preposition Traps in TOEFL Writing and Speaking

A student is reading their Academic Discussion response one last time. "I agree to my classmate's point because the success of the policy depends from how strictly it is enforced. Different from what some people think, the issue is similar with the one we discussed last week." Three preposition errors in two sentences — and the 10-minute writing timer has only 45 seconds left.

Prepositions are the smallest words in English with the biggest power to make a sentence sound off. Depend on. Focus on. Agree with. Interested in. Similar to. Different from. Each of these pairings is fixed. There's usually no logical reason why the verb takes one preposition and not another. They just do, and English speakers learn them as units.

On the TOEFL, prepositions cause two problems. First, the verb-preposition pairs have to be memorized — there's no rule that lets you derive them. Second, the time and place prepositions (in, on, at, by, until, for, since) follow soft rules with real exceptions, and the soft rules break under time pressure.

This article gives you the highest-value preposition pairs for TOEFL Writing and Speaking, plus the time and place traps that show up most.

Why This Matters on TOEFL iBT 2026

Prepositions are a high-frequency error type. A test-taker who struggles with prepositions will make six or seven small mistakes across a single Writing task. Each error is minor. Together, they signal to the scorer that language use is uneven.

In Speaking, prepositions are very audible. "I'm interested at this topic" sounds wrong to any English ear. "I'm interested in this topic" sounds natural. The substitution is tiny but the impression is large.

In Writing, especially formal Writing, prepositions affect clarity. "The success depends from training" is grammatically wrong; even if a scorer can guess the meaning, the error stops the reader for a moment. A response with multiple preposition errors becomes tiring to read.

In Reading, prepositions sometimes carry meaning that distractor options exploit. "The policy was supported by the committee" (active agent) versus "The policy was supported until the committee changed" (time limit) — two very different statements.

The Trap

There are three preposition traps.

1. Verb-preposition pairs. These are fixed combinations that have to be memorized. The highest-value pairs for TOEFL Writing:

• depend on, rely on, count on, base X on Y
• focus on, concentrate on, work on
• agree with (a person), agree on (a plan or topic), agree to (a proposal)
• different from (American academic standard), similar to
• interested in, involved in, succeed in, participate in
• aware of, afraid of, capable of, consist of
• responsible for, suitable for, famous for

2. Time prepositions (in, on, at, by, until, for, since). The soft rules:

• In + month, year, season, century, long period. In March. In 2026. In the past.
• On + specific day or date. On Monday. On May 26.
• At + clock time, specific point. At 3 p.m. At noon. At the moment.
• By + a deadline (action complete before this point). Finish by Friday.
• Until + a stopping point (action continues up to this point). Work until Friday.
• For + duration. For three years.
• Since + a starting point. Since 2020.

3. Place prepositions (in, on, at, between, among). Soft rules:

• In + enclosed space or large area. In the room. In the city.
• On + surface or line. On the table. On the road.
• At + specific point or address. At the entrance. At 25 Main Street.
• Between + two distinct entities, or among multiple but treated as pairs/discrete units. Between you and me. The contract between three companies.
• Among + more than two, treated as a group. Popular among students.

Wrong / Better / Why

Where It Shows Up

Academic Discussion responses. Sentences of opinion are full of preposition pairs. "I agree with the professor's view. The success depends on consistent practice. I'm focused on the long-term benefits." If any of these pairs is wrong, the response reads as rough.

Write an Email. Formal emails use prepositions in fixed phrases that need to be exact. "I am writing to inquire about the program." (Not "for the program," not "of the program.") "Thank you for your prompt response." (Not "by your response.") See What's the Right Way to Write an Email on the TOEFL 2026? for the broader register issue.

Take an Interview. Spoken answers constantly use "interested in," "good at," "different from," "similar to." Under time pressure, prepositions slip. "I'm good in math" (wrong — should be "good at math").

Listen to a Conversation. When you track a student's reaction to a policy, "The student agrees with the policy" can raise a useful question: with the policy itself, or with the person who made it? The preposition choice clarifies which.

Write for an Academic Discussion. Reporting verbs and academic discussion phrases all need correct prepositions. "The author argues against the position." "The professor provides evidence for the opposing view." "The findings differ from previous research." These are exactly the kinds of sentences scorers expect to see — and exactly where preposition errors show up.

Fast Fix

A practical approach to preposition control:

• Build a personal list of the 20 verb-preposition pairs you actually use. Don't try to memorize a textbook list of 200. Pick the 20 you'd use in a TOEFL Writing response and drill those. Examples: depend on, focus on, agree with, similar to, different from, interested in, aware of, responsible for.
• For time, anchor with the "zoom" trick. Long stretch → in (in 2026, in March). Specific day → on (on Monday). Clock point → at (at 3 p.m.). This works the same way for place: country/city → in, surface → on, specific point → at.
• For deadlines, distinguish "by" and "until." By = complete before. Until = continue up to. Finish by Friday vs. Work until Friday.
• For "since" and "for," check tense. Both pull present perfect: I've lived here since 2020 / for five years.
• Never write "on the past." It doesn't exist. "In the past" is the fixed phrase.

For verb-preposition pairs you're unsure about, the safest rescue is to rephrase. Instead of risking "I'm responsible for handling the project," you can write "I handle the project." Cleaner, safer, and you avoid the preposition decision entirely.

Mini Practice

Fill in the right preposition.

1. The results of this study are different _____ what previous researchers found.
2. Please submit the assignment _____ Friday at noon. (deadline; complete before)
3. The professor focuses _____ environmental policy in her current research.
4. I am writing _____ inquire _____ the graduate program in linguistics.
5. The disagreement _____ the three departments has lasted for years.

What to Check Before You Submit

• Scan for the verb-preposition pairs you used. Any that look "translated" from another language pattern? Re-check.
• Did you use "different from" rather than "different than" or "different of" in formal Writing?
• For deadlines, is it "by" (complete before)? For ongoing actions up to a point, is it "until"?
• Any "on the past"? Replace with "in the past."
• For groups, did you use "among" for more than two and "between" for two (or for distinct pairs within a group)?

A final reminder: prepositions in English are mostly arbitrary. There's no satisfying logical reason why we depend on but consist of but participate in. The fix is exposure and repetition, not analysis. Build the list, drill the list, and check the list during your final 30 seconds of Writing review. That's the highest-yield use of pre-submit time on the entire TOEFL Writing section.