The correct answers are:
- while
- After
- before
While is used here to show that an action (dropping the screwdriver) interrupted an ongoing, continuous past action ("was sprinting").
After establishes a logical sequence: first locking the doors, then taking a breath of relief.
Before creates a strict deadline—the battery must be recharged prior to the meteor strike, or our time traveler is doomed!
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.
Verb tense
If you've ever frozen mid-sentence wondering whether to say I worked or I have worked, I had been doing or I was doing — you've felt the weight of English's tense system. Twelve forms, each with a specific job, and the wrong choice subtly misrepresents your meaning. Mastering tenses is the longest single project in English grammar, but it's also the one with the biggest payoff.
Verb tense signals when an action happens. English has three time references (past, present, future) combined with three aspects (simple, progressive, perfect), giving twelve standard forms. Each carries a specific meaning beyond just timing.
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.
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.
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.