The correct answers are at, at, the, and an.
at home / at midnight: In English, we use "at" for specific locations like home or work, and for specific clock times like midnight. (Turkish speakers often use the locative suffix -de/-da for all of these, which can make choosing between in, on, and at tricky!)
the roof: We use "the" because we are talking about a specific roof (the roof of the museum).
an unusually: We use "an" instead of "a" because the next word (unusually) starts with a vowel sound.
Preposition
- ✅ interested in — ❌ interested on
- ✅ good at football — ❌ good in football
- ✅ depend on — ❌ depend of
- ✅ arrive at the station — ❌ arrive to the station
Prepositions link nouns to the rest of the sentence: time (at 5pm), place (in London), manner (with care), abstract (afraid of). Most are idiomatic — the "correct" preposition must be memorised with each verb/adjective combination.
Rule: there is no universal rule. English prepositions are learned by combination: interested IN, good AT, depend ON, afraid OF. Your native language's equivalent will often mislead.
Article
- ✅ an hour — ❌ a hour (vowel sound → an)
- ✅ a university — ❌ an university (consonant sound /j/ → a)
- ✅ I love coffee — ❌ I love the coffee (generic uncountable → zero article)
- ✅ the sun — ❌ a sun (unique referent → the)
Articles (a/an, the, and the zero article) signal whether a noun is specific or general. A/an introduces something new; the points to something already known or unique.
Pattern: a/an = "one of many, first mention." The = "you know which one." Zero article = generic or uncountable.
B1 | Intermediate
- ✅ If I had more time, I would travel more. — second conditional
- ✅ The bridge was built in 1920. — passive voice
- ✅ She said she was tired. — reported speech with backshift
- ✅ Although it rained, we enjoyed the trip. — complex sentence with concession
These are B1 patterns — the CEFR intermediate level. At B1 you link ideas, use passive voice, handle reported speech, and manage second conditional — enough for travel, work basics, and everyday independence.
Marker: if you can explain why something happened and follow a news story, you're B1.
Medium
- If I were you, I would apologise. — one rule (second conditional), but distractors like was tempt you
- Answers require active thought, not instant pattern recognition
- Vocabulary and context are realistic, not artificially simplified
- Usually tests one rule, but the wrong answers are plausible
Medium marks middle-difficulty challenges: A2–B1, one rule tested, but with realistic distractors that require genuine understanding.
Use "Medium" when Easy feels too obvious but Hard feels overwhelming. This is where most productive learning happens — the sweet spot of difficulty.