interested or interesting? Master the "Adjective + Preposition" Combinations Learners Get Wrong Most Often
When you want to say "I'm interested in music," do you translate word-for-word from your native language in your head, ending up with I'm interesting in music.? The grammar might seem logical, but native speakers can immediately spot it as unnatural English.
Where is the problem? In many languages, there are few fixed rules about which prepositions follow an adjective. In English, however, every adjective is bound to its own specific preposition. Often there is no logical explanation for it—you simply have to memorize the whole pair.
The good news is that the combinations learners mess up are usually limited to a few high-frequency phrases. Today, we'll go through them one by one using a "✗ Unnatural English → ✓ Natural Expression" comparison to memorize the trickiest ones.
The #1 Pitfall: interested or interesting?
This error actually involves two mistakes at once, which is why it comes first.
- ✗ I'm interesting in music.
- ✓ I'm interested in music.
First mistake: interested or interesting.
- interested = someone "feels" interested (the feeling originates from a person)
- interesting = something "is" interesting (the thing itself causes interest)
Therefore, when a person is the subject, you almost always use interested:
- I'm interested in this course. ✓
- This course is interesting. ✓
A quick test: If you are saying "I feel...", and the subject is a person, use -ed (interested, bored, tired, excited). If you are describing what the thing "itself is like," use -ing (interesting, boring, tiring, exciting).
Second mistake: interested must be followed by in.
- ✗ I'm interested on science.
- ✓ I'm interested in science.
good goes with at
When expressing high ability in a subject, many learners intuitively say good in math because it sounds like "good in the field of math."
- ✗ She's good in math.
- ✓ She's good at math.
To express being skilled at something, good always pairs with at, whether it's a school subject, a sport, or a skill:
- He's good at cooking. ✓
- I'm not very good at drawing. ✓
A handy opposite to remember: to express lack of skill, use bad at or terrible at—the preposition remains at.
- I'm bad at remembering names. ✓
afraid fears of
It is easy to translate "afraid" as afraid from spiders because it feels like the fear has a starting point or source. In English, the correct expression is:
- ✗ He's afraid from spiders.
- ✓ He's afraid of spiders.
No matter what you fear, afraid is always followed by of:
- I'm afraid of the dark. ✓
- Don't be afraid of making mistakes. ✓
Here's a small conversational tip. In everyday spoken English, native speakers often use scared, which sounds more casual and natural than afraid. The preposition is also of:
- I'm scared of dogs. ✓
Another common confusion: if you want to say "I feel uneasy about tomorrow's interview," use nervous, not afraid.
- ✗ I'm afraid about the interview.
- ✓ I'm nervous about the interview.
Rule of thumb: Use afraid / scared for fearing a specific thing or event happening; use nervous about for feelings of anxiety or tension.
worried goes with about
Saying "I am worried about the exam" often gets mistranslated as worried for the test, but for is incorrect here.
- ✗ I'm worried for the test.
- ✓ I'm worried about the test.
When worrying about something, worried pairs with about:
- She's worried about her son. ✓
- Don't worry about it. ✓
A quick note: worried for someone can be correct in certain contexts, carrying a meaning closer to "feeling concerned on someone's behalf." For A1–B1 learners, treat worried about as your default answer, and you will almost always be right.
A Cheat Sheet for High-Frequency Mis-pairings
Here is a quick reference table summarizing today's main points. Whenever you feel unsure, check this list:
- ✗ interesting in / interested on → ✓ interested in
- ✗ good in → ✓ good at
- ✗ afraid from → ✓ afraid of / scared of
- ✗ worried for → ✓ worried about
Here are a few more high-frequency combinations to learn at the same time:
- proud of: I'm proud of you. ✓
- excited about: We're excited about the trip. ✓
- angry with (person) / angry about (thing): She's angry with me. ✓
- famous for: Taiwan is famous for bubble tea. ✓
A Takeaway Memorization Strategy
Don't memorize adjectives and prepositions separately. Treat the pair as a "single word"—for instance, interested-in, good-at, afraid-of, worried-about. Say them aloud a few times together, and they will naturally stick.
The most effective memory trick is to put the phrase into a sentence about yourself:
- I'm interested in photography.
- I'm worried about my speaking.
Your brain remembers much better when the sentence is personally relevant to you.
How to Practice in Loopy
Simply reading a table isn't enough to memorize these "adjective + preposition" combinations. You need to encounter them repeatedly in real sentences for them to become second nature.
Loopy incorporates high-frequency collocations like interested in, good at, and afraid of into the real conversations of its level-based courses. Whatever your level (A1, A2, or B1), the system serves content tailored to you, guiding you step by step. Every phrase you practice enters a memory curve review system, reappearing right as you are about to forget it, helping you transition from "thinking hard" to "speaking effortlessly."
When you hear a combination you aren't sure about, tap the built-in dictionary to view example sentences and the correct preposition. To practice speaking naturally, use the listening and shadowing mode to read the full phrase along with native speakers, turning interested in and worried about into muscle memory. Making mistakes is perfectly okay—that's right where progress begins.
Want to know your current proficiency level and which course tier you should start with? Take a quick test to find out!