33%
You are reading a top-secret manual for surviving a vampire attack. Select ALL the grammatically correct options to complete this crucial safety rule.
"If you hear a knock at your window at midnight, you ________ keep the door locked!"

The correct answers are must, have to, and have got to.

All three of these options correctly express strong obligation or necessity for the pronoun "you".

Have got to is a slightly more informal (but perfectly correct) way to say have to.

"Must to" is incorrect because modal verbs are followed by a bare infinitive (no "to"). "Has to" is incorrect because it is only used for third-person singular subjects (he/she/it).

To ChallengesPreviousNext

Modal verb

If you've ever struggled with the difference between You must do this (strong command) and You should do this (advice) — or It might rain (possible) and It will rain (certain) — you've felt how much modal verbs do in English. They're how the language signals certainty, obligation, possibility, and politeness, and getting them right is what stops your speech from sounding either pushy or wishy-washy.

A modal verb is an auxiliarycan, could, may, might, must, shall, should, will, would — adding meaning around ability, permission, possibility, obligation, or speculation. Always followed by the bare infinitive (can swim, never can to swim), and never inflected for person.

English grammar

If you can speak English but feel you're forever guessing — should that be a/the?, would have been or had been?, who or whom? — you don't have a vocabulary problem; you have a grammar problem. Grammar is the system that turns isolated words into precise meaning, and the only difference between guessing and knowing is studying it deliberately.

English grammar is the system of rules that govern how meanings are encoded in English: word formation, phrase and sentence structure, tenses, agreement, word order, and punctuation.

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.

Humor

If you've ever reached the third drill of present perfect and felt your eyes glaze over, you've hit the limits of dry repetition. Practice that's even mildly funny is far easier to come back to — and far easier to remember weeks later. That's the whole point of the Humor tag.

The Humor tag marks questions where the author has tried to make the practice entertaining alongside instructive. Subjective, sometimes silly, but designed to keep you engaged long enough for the rule to stick.

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: Easy

If a textbook leaves you confused, sometimes the issue isn't the topic — it's that the practice material is layered with extra complications. Filtering by Easy strips that away. You get one rule at a time, in plain everyday language, with no trick questions. It's how you make a shaky foundation solid before stacking more on top.

The Easy difficulty tag marks beginner-level questions and challenges — typically A1 or early A2. Single-rule focus, short sentences, common vocabulary, one clear correct answer.