The correct answers are had known and would have come.
In third (past unreal) conditionals, use "if + past perfect" and "would have + past participle" to express regrets or hypothetical situations in the past.
Conditional sentence
Second vs third conditional: second = unreal present/future (If I had money, I would buy it — but I don't have money now). Third = unreal past (If I had studied, I would have passed — but I didn't study). The most common confusion: using second when you mean third, making your timeline unclear.
A conditional sentence = if-clause + consequence clause. Five patterns (zero, 1st, 2nd, 3rd, mixed) each encode a specific time and probability.
Diagnostic: is the hypothetical about now or then? Now → second conditional. A past event that didn't happen → third conditional.
Subjunctive mood
Subjunctive vs indicative: indicative states facts (He goes every day). Subjunctive marks unreality (I suggest he go; If I were you). The subjunctive drops the -s and insists on were — signalling "this isn't (or may not be) real." In informal speech it's disappearing, but formal/academic writing still expects it.
The subjunctive mood = hypothetical/counterfactual marker. Present subjunctive (base form after suggest/demand/insist that). Past subjunctive (were in unreal conditionals).
Diagnostic: is the clause about something unreal, demanded, or recommended (not yet true)? → subjunctive. Is it factual? → indicative.
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.
Hard
Hard vs Medium: Medium tests one rule with realistic distractors. Hard tests interacting rules, edge cases, or context-dependent answers where multiple options seem correct until you think deeply. If you're scoring 80%+ on Medium, try Hard to find your real gaps.
The Hard tag filters for B2+ challenges with layered difficulty: rule interactions, subtle distractors, and contexts that demand genuine grammatical reasoning.
Diagnostic: if Hard questions feel impossible, drop to Medium and master the individual rules first. Hard assumes you already know each rule — it tests whether you can apply them together.