The correct answers are a, on, in, and the.
a history teacher: In English, you must always use an article (a/an) before a singular profession. (In Turkish, it's common to say "I am teacher," but in English, you must say "I am a teacher.")
on May 4th: We use "on" for specific dates. If it were just the month (May), we would use "in".
in the morning: Parts of the day (morning, afternoon, evening) take "in".
the sun: We use "the" for unique objects in our universe, like the sun, the moon, and the sky.
Preposition
Preposition vs particle: same words (in, on, up, off), different jobs. A preposition links to a noun (look at the book). A particle changes verb meaning without a noun (give up = quit). Test: is there a noun/pronoun after it forming a prepositional phrase? → preposition. Does it change the verb's meaning? → particle in a phrasal verb.
A preposition = small word connecting a noun to the sentence (time, place, manner, relationship). Choice is idiomatic per verb/adjective combination.
Diagnostic: struggling with which preposition to use? It's almost never about logic — look up the specific verb/adjective + preposition combination.
Article
A/an vs the vs no article: the three-way choice that trips up learners whose first language has no articles (Russian, Japanese, Korean, Mandarin). Each option changes meaning — I saw a dog (any dog) vs I saw the dog (the specific one) vs Dogs are loyal (the species).
Articles are determinatives that mark noun specificity. A/an = indefinite, first mention. The = definite, known referent. Zero article = generic or uncountable.
Diagnostic: ask does the listener already know which one? Yes → the. No, and it's countable singular → a/an. Generic or uncountable → zero article.
Humor
Humor vs serious practice: both teach the same rules. The difference is engagement — funny material keeps you coming back and creates stronger memory hooks. If dry drills bore you into quitting, humorous practice is more effective because you actually do it.
The Humor tag filters for entertaining practice: silly contexts, wordplay, absurd examples — all testing real grammar rules underneath.
Diagnostic: if you find yourself dreading practice → try filtering by Humor. If you're preparing for a formal exam and want serious register → filter it out.
B1 | Intermediate
B1 vs B2: B1 handles standard everyday communication and simple opinions. B2 handles abstract topics, sustained arguments, and nuanced register. If you can chat about your life but struggle to debate an issue or write a formal essay, you're B1.
B1 is the intermediate CEFR level: independent handling of familiar topics, second conditional, basic passive, reported speech, and linking words for cause and contrast.
Diagnostic: can you read a newspaper article on a familiar topic and summarise the argument? Comfortably → B2. Struggle with abstractions → still B1.
Medium
Medium vs Easy: Easy has one obviously correct answer and clearly wrong distractors. Medium has one correct answer but plausible distractors — you need to actually know the rule, not just guess from sound.
The Medium tag filters for A2–B1 challenges with realistic difficulty: one rule per question, plausible alternatives, everyday contexts.
Diagnostic: if you're scoring 90%+ on Easy, move here. If you're below 60% on Medium, go back to Easy for that topic. Target 70–80% accuracy for maximum learning.