Choose the correct pair of words to complete the roommate's baffled sticky note.
"There is a glowing green jar of mayonnaise in the fridge. _____ on earth did you buy that _____?"
The correct answer is What / for.
To ask about the purpose or reason for something, we often use the combination of What at the beginning of the question and for at the end. "What... for?" means the same thing as "Why?", but notice that we never say "Why... for?".
Questions
Questions in English are typically formed by inverting the subject and an auxiliary verb: She can dance → Can she dance?. When there's no auxiliary present, English adds do-support: The milk goes in the fridge → Does the milk go in the fridge?. The same pattern handles wh-questions (Where do you live?) and negative questions (Doesn't he know?).
The trickiest variant is indirect questions — I wonder where he is, not where is he. The inversion drops because the question is embedded inside another clause. Getting this right is one of the bigger jumps from A2 to B1 fluency.
Preposition
A preposition is a small word that links a noun or noun phrase to other parts of the sentence — usually marking time, place, or relationship: in, on, at, to, from, with, over, under, between, during. The book on the table, We met at noon, She lives in Berlin.
Prepositions are deceptively small. Their meaning shifts dramatically by collocation (depend on, good at, afraid of), and their choice rarely translates directly between languages. Picking the right preposition is one of the trickiest, most idiomatic-sounding parts of English.
English Grammar Basics
The English Grammar Basics tag marks quizzes and explainers covering the foundations of English grammar — nouns, verbs, adjectives, adverbs, prepositions, conjunctions, tenses, voice, mood, and basic sentence structure.
If you're starting out or rebuilding from scratch, this is the tag to follow: every challenge under it is designed to land the core rules without burying you in exceptions. Get the basics solid here and the more advanced topics — conditionals, reported speech, inversion — stop looking like a wall of new rules and start looking like extensions of what you already know.
Vocabulary
The Vocabulary tag groups practice that focuses on words rather than grammar rules — common words, collocations, phrasal verbs, idioms, and the lexical patterns native speakers reach for instinctively. It cuts across grammar topics, offering targeted vocabulary work at every CEFR level from A1 to C2.
Grammar gets you the structure of English; vocabulary gets you the colour. Plenty of B1 grammar with A2 vocabulary still sounds simple; the right word at the right register is what shifts your English from "correct" to "natural".
Humor
The Humor tag marks questions and challenges where the author has tried — subjectively, deliberately — to make the practice itself entertaining. Expect characters, scenarios, and storylines that play with absurdity: zombies, alien tourists, a chef's disaster, a roommate's complaint. The grammar rule is real; the wrapping isn't.
Humor matters because grammar drills are forgettable. Tying a rule to a story your brain wants to keep makes it stick. Filter by Humor when motivation is what you're short on, not study time.
B1 | Intermediate
B1 is the intermediate level in the CEFR framework — the point where you stop relying on memorised phrases and start handling everyday English independently. At B1 you can describe experiences, explain opinions, and follow most clear standard speech on familiar topics like work, travel, and hobbies.
Grammatically, B1 means combining tenses with precision, building complex sentences, and starting to use passive voice, modal verbs for necessity and possibility, and verb patterns (gerund vs. infinitive). Knowing your level shapes what you study next: pushing too far ahead frustrates you; staying below your level wastes time.
Difficulty: Medium
The Medium difficulty tag marks questions and challenges in the middle of the difficulty range — typically suitable for A2 to B1 learners. Expect a single rule with realistic distractors, longer sentences, and contexts where you have to think before answering rather than reading off the obvious choice.
Filter by Medium when you're past the absolute basics and ready to consolidate. It's the level where most lasting progress happens — easy enough that you can finish without exhausting concentration, hard enough that getting it right means you've actually understood.