The correct answers are I had left and if I liked.
Reported Wh- Questions: We keep the question word (why) but change the word order to a normal statement (Subject + Verb). We also backshift the tense (past simple did leave becomes past perfect had left).
Reported Yes/No Questions: We use if or whether and apply the same statement word order (Subject + Verb). "Do you like alpacas?" becomes "if I liked alpacas."
Indirect speech
Direct vs indirect speech: direct speech quotes exact words (She said, "I am tired."). Indirect speech reports the meaning (She said she was tired.). The key difference is backshift — tenses move one step into the past when the reporting verb is past tense.
Indirect speech = reported words without quotation marks. Core mechanism: backshift (present→past, past→past perfect, will→would) + pronoun/time shifts.
Diagnostic: is the reporting verb past (said, told)? → backshift required. Is it present (says, tells)? → no shift needed. Exception: universal truths don't shift (He said the Earth is round).
Questions
Direct vs indirect questions: direct questions invert and end with ? (Where does she live?). Indirect questions DON'T invert and end with a period (I wonder where she lives.). Mixing these up — I wonder where does she live? ❌ — is one of the most common structural errors.
Questions in English use inversion/do-support. Types: yes/no, wh-, negative, tag. Direct questions invert; indirect don't.
Diagnostic: is your question embedded inside a statement (I wonder, Do you know, Can you tell me)? → DON'T invert. Is it a standalone question? → invert.
Word order
English (SVO) vs other patterns: English relies on word ORDER to show who does what (Dog bites man ≠ Man bites dog). Inflected languages (Latin, Russian, German) use case endings and can scramble order freely. In English, changing order changes meaning or requires special constructions (inversion, cleft sentences).
Word order = how English marks grammatical relationships. SVO is the default; fixed adjective order; adverb placement varies by type.
Diagnostic: does your sentence sound "off" even though all word forms are correct? → probably a word order issue. Try moving the element back to default SVO position.
Verb tense
Tense vs aspect: tense locates the action in TIME (past/present/future). Aspect describes its SHAPE — is it completed (perfect), ongoing (progressive), or just a fact (simple)? English combines these independently: was working = past (tense) + progressive (aspect). Confusing tense with aspect is why the 12-form grid feels overwhelming.
Verb tense = 3 time references × 3 aspects = 12 forms. Tense says when; aspect says how the action unfolds relative to that time.
Diagnostic: wrong time? → tense error. Right time but wrong "shape" (e.g., I work here for ten years instead of I've worked)? → aspect error.
B2 | Upper Intermediate
B2 vs C1: B2 means effective communication on complex topics with some effort. C1 means effortless fluency with precise register control. If you can argue a point but still reach for words and make structural slips under pressure, you're B2.
B2 is the upper-intermediate CEFR level: mixed conditionals, complex passives, reported speech with backshift, participle clauses, and sustained written argument.
Diagnostic: does your writing read as "competent non-native" or "could be native"? The former → B2. The latter → C1.
Medium
Medium vs Easy: Easy has one obviously correct answer and clearly wrong distractors. Medium has one correct answer but plausible distractors — you need to actually know the rule, not just guess from sound.
The Medium tag filters for A2–B1 challenges with realistic difficulty: one rule per question, plausible alternatives, everyday contexts.
Diagnostic: if you're scoring 90%+ on Easy, move here. If you're below 60% on Medium, go back to Easy for that topic. Target 70–80% accuracy for maximum learning.