The correct answers are What is this bizarre gadget used for? and For what is this bizarre gadget used?
When asking about purpose, we use "What... for?". The most natural and common way to ask this in English is to leave the preposition "for" at the end of the question.
Moving the preposition to the front ("For what is this...") is grammatically correct but sounds quite formal or old-fashioned.
The option missing "for" is incorrect because "used" requires the preposition to indicate purpose. The final option is incorrect because it lacks the necessary subject-verb inversion for a question (it should be "is this", not "this is").
Questions
If you've ever asked You like coffee? with rising intonation and gotten a confused look — you've felt the gap between casual and grammatical English questions. Many languages form questions with intonation alone, but English usually requires inversion (Are you ready?) or do-support (Do you like coffee?). Skip the structure and your questions sound like uncertain statements.
Questions in English use inversion of subject and an auxiliary (Can she dance?) or do-support when no auxiliary is present (Does the milk go in the fridge?). Yes/no questions, wh-questions, negative questions, and tag questions all share this machinery.
Preposition
If you've ever written I'm interested on you (should be in) or I'm good on football (should be at) — you've hit prepositions' main pitfall. Their choice is mostly idiomatic, not logical, and rarely matches what your native language does. Memorising the right preposition for each common verb and adjective is what stops your speech from sounding subtly off.
A preposition is a small word linking a noun or noun phrase to other parts of the sentence: in, on, at, to, from, with. Marks time, place, manner, or abstract relationships. Choice is largely idiomatic, especially in fixed combinations (depend on, good at, afraid of).
Word Order
If your first language has flexible word order — Russian, Latin, German, Japanese — English can feel rigid. You can't just rearrange words for emphasis the way you would at home; the grammar tracks position, not just inflection. Get the order wrong and the sentence either changes meaning or stops making sense.
Word order is the sequence of words in a sentence. English is an SVO language — subject, verb, object. The order of adjectives and modifiers in a noun phrase also follows fixed patterns. Get this right and your English instantly sounds more natural.
English Grammar Basics
If grammar feels like a tangle of rules you can never quite remember, the fix isn't more advanced material — it's making the foundations automatic. The English Grammar Basics tag is where you do that: the building blocks every other topic stands on. Get these right and the rest stops feeling random.
It marks quizzes and explainers covering the core of English: nouns, verbs, adjectives, adverbs, prepositions, conjunctions, tenses, voice, mood, and basic sentence structure. Useful whether you're a beginner or refreshing rusty knowledge.
B1 | Intermediate
If you can hold a conversation about your weekend, explain why you're late, and follow a short news story without panicking — but still feel lost in fast or technical English — you're probably operating at B1. Knowing this matters: study material at the wrong level either bores you or burns you out, and B1 is the typical target for travel, casual work, and most everyday social English.
B1 is the intermediate level in the CEFR framework, where you handle everyday English independently and start combining ideas with complex sentences, passive voice, and modal verbs.
Difficulty: Medium
If easy questions feel too obvious but hard questions leave you guessing, you're probably ready for Medium — the level where most real learning happens. It pushes just enough to expose the rules you don't quite have yet, without burying you in edge cases. This is where steady fluency is built, one well-aimed challenge at a time.
The Medium difficulty tag marks middle-range challenges — typically A2 to B1. One rule per question, realistic distractors, and contexts that require active thought rather than instant recognition.