The correct answers are Leo fell asleep during the movie. and Leo fell asleep while he was watching the movie.
Use during before a noun (like "the movie") to say when something happens.
Use while before a subject and a verb (like "he was watching") to show two things happening at the same time.
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).
Conjunction
If your writing reads like a list of separate sentences — I was tired. I went home. I slept badly. — the missing piece is conjunctions. They're how you bind ideas together: I was tired, so I went home, but I still slept badly. Pick the wrong one and the relationship between ideas flips; pick none and your writing stays choppy.
A conjunction connects words, phrases, or clauses. Coordinating conjunctions (and, but, or, so, yet, for, nor) link equal units; subordinating conjunctions (because, although, if, when, while) introduce dependent clauses.
Clause
If you've ever been told your sentence is a "run-on" or that you've used a comma where there should be a semicolon — you've hit the limits of writing without seeing clauses. Get this concept solid and most punctuation problems quietly disappear: you can finally tell a complete thought from a fragment without guessing.
A clause is a grammatical unit built around a verb, usually with a subject and a predicate. Independent clauses stand alone (I missed the bus); dependent clauses can't (Because I overslept). Combine them and you build complex sentences.
Past tense
If you've ever told a story in English and felt the timeline get tangled — I came home, the dog ate, the cat slept — you've hit the limits of using simple past for everything. The past tense system has four forms specifically because real stories have layered timing: things that happened before other things, actions caught in progress, sequences of completed events.
The past tense has four English forms: simple past (I walked), past progressive (I was walking), past perfect (I had walked — earlier than another past event), past perfect progressive (I had been walking — ongoing up to a past point). Plus irregular verbs for the simple-past form.
A1 | Elementary | Beginners
If you can say your name, ask Where is the toilet?, and read a simple bus sign — but freeze when someone speaks at normal speed — you're at A1. That's not a problem to fix; it's the level where most learners actually live for a while, and recognising it lets you pick the right material instead of drowning in advanced grammar that wasn't meant for you yet.
A1 is the starting level of the CEFR framework, covering basic everyday communication: greetings, introductions, simple personal questions, present-tense forms of be/have/do, and core determiners and prepositions.
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.