The correct answers are I was taking a shower when the lights suddenly went out. and When the power failed, my cat was sleeping on my face.
We use the past continuous (was/were + verb-ing) for a longer background action that gets interrupted by a shorter action in the past simple (like the power failing).
"I" and "my cat" (singular) both require the auxiliary verb was, not "were". Furthermore, you cannot omit the auxiliary verb "was" before the "-ing" verb.
Progressive tense
Progressive vs simple: I work in London (permanent job) vs I am working in London (temporary assignment). Simple = fact/habit/permanent. Progressive = ongoing/temporary/in-progress. Same verb, different aspect, different meaning. The choice isn't about grammar preference — it changes what you're communicating.
The progressive = be + -ing. Marks ongoing/temporary actions. Stative verbs resist it.
Diagnostic: is the action happening RIGHT NOW and likely to stop? → progressive. Is it a general truth, habit, or scheduled event? → simple. Is the verb stative (know, own, believe)? → simple (even if happening now).
Past tense
Simple past vs past perfect: simple past puts events on the main timeline (I arrived. She left.). Past perfect marks an event as earlier than another past event (She had left before I arrived). If all events are in sequence, simple past is enough. Only use past perfect when you need to show "earlier than the main story."
The past tense has four forms encoding different temporal relationships: simple past, past progressive, past perfect, past perfect progressive.
Diagnostic: are events in sequence? → simple past is fine. Need to show one event happened before another past event? → past perfect for the earlier one.
English grammar
Grammar vs vocabulary: vocabulary gives you the words; grammar gives you the system for combining them into meaning. Knowing 10,000 words without grammar produces incoherent sentences. Knowing grammar with limited vocabulary produces clear, correct sentences about fewer topics. Both matter — but grammar is the framework.
English grammar is the complete rule system: parts of speech, phrase and sentence structure, tenses, agreement, word order, and punctuation.
Diagnostic: if your sentences are understood but "sound wrong" → grammar issue. If you can't find the right word → vocabulary issue. If both → start with grammar.
A2 | Elementary | Pre-intermediate
A2 vs B1: A2 handles routine transactions and simple past narration. B1 handles connected discourse, explaining reasons, and understanding main points in clear standard speech. If you can tell what happened but not why it matters, you're still A2.
A2 is the elementary level of the CEFR: past simple, present perfect, first conditional, basic modals, and routine communication about familiar topics.
Diagnostic: can you link ideas with because, although, so that and hold a conversation beyond scripted topics? No → A2. Yes → moving into B1.
Easy
Easy vs Medium vs Hard: Easy = one rule, obvious answer, A1–A2. Medium = one rule but realistic distractors, A2–B1. Hard = interacting rules, edge cases, B2+. Start Easy to check you have the basics before moving up.
The Easy tag filters for single-rule, short-sentence, common-vocabulary challenges designed for beginners or for anyone wanting a confidence check on fundamentals.
Diagnostic: if you get Easy questions wrong, stay here — your foundations need work. If they feel trivial, move to Medium.