Conditional sentence

• ✅ If you heat ice, it melts. — zero conditional (always true)
• ✅ If it rains, I'll take an umbrella. — first conditional (real future)
• ✅ If I had wings, I would fly. — second conditional (unreal present)
• ✅ If I had left earlier, I would have caught the train. — third conditional (unreal past)

Conditional sentences pair an if-clause with a consequence. Five patterns (zero through mixed) each combine specific tenses to express different levels of reality and time.

Pattern: the tense in the if-clause is always one step "back" from what you'd expect — past for present hypotheticals, past perfect for past hypotheticals.

Modal verb

• ✅ She can swim. — ❌ She can to swim. (modal + bare infinitive, no to)
• ✅ You must leave now. — strong obligation
• ✅ It might rain. — possibility (~50%)
• ✅ He should apologise. — advice/recommendation

Modal verbs (can, could, may, might, must, shall, should, will, would) are auxiliaries expressing ability, permission, possibility, obligation, or speculation. Always + bare infinitive. Never inflected (she can, not she cans).

Rule: modals never take to after them, never add -s for third person, and can't combine directly (must can ❌ — use must be able to).

Past tense

• I walked home. — simple past (completed action)
• I was walking when it rained. — past progressive (in progress)
• I had already left when she arrived. — past perfect (earlier past)
• I had been waiting for an hour. — past perfect progressive (duration up to a past point)

Four past tense forms: simple past (done), past progressive (was happening), past perfect (had already happened), past perfect progressive (had been happening). Each encodes different timing relative to other past events.

Pattern: simple past = the story's main timeline. Past progressive = background action. Past perfect = flashback to something even earlier.

Verb mood

• Indicative: She goes every day. — stating fact
• Imperative: Go now. — giving command
• Subjunctive: I suggest she go. — hypothetical/recommendation
• Conditional: She would go if asked. — dependent on condition

Verb mood marks the speaker's attitude: indicative (fact), imperative (command), subjunctive (unreal/recommended), conditional (would/could). English barely marks mood morphologically — mostly through auxiliaries and word order.

Rule: stating a fact? → indicative. Giving a command? → imperative. Imagining/recommending? → subjunctive or conditional. The mood determines which verb forms and auxiliaries you use.

Verb tense

Verb tense = time (past/present/future) × aspect (simple/progressive/perfect) = 12 forms. Each slot has a specific job — not just "when" but "how the action relates to its time frame."

Key insight: most learners don't need all 12 at once. Simple covers 80% of communication. Add perfect and progressive as needed.

B1 | Intermediate

• ✅ If I had more time, I would travel more. — second conditional
• ✅ The bridge was built in 1920. — passive voice
• ✅ She said she was tired. — reported speech with backshift
• ✅ Although it rained, we enjoyed the trip. — complex sentence with concession

These are B1 patterns — the CEFR intermediate level. At B1 you link ideas, use passive voice, handle reported speech, and manage second conditional — enough for travel, work basics, and everyday independence.

Marker: if you can explain why something happened and follow a news story, you're B1.

Medium

• If I were you, I would apologise. — one rule (second conditional), but distractors like was tempt you
• Answers require active thought, not instant pattern recognition
• Vocabulary and context are realistic, not artificially simplified
• Usually tests one rule, but the wrong answers are plausible

Medium marks middle-difficulty challenges: A2–B1, one rule tested, but with realistic distractors that require genuine understanding.

Use "Medium" when Easy feels too obvious but Hard feels overwhelming. This is where most productive learning happens — the sweet spot of difficulty.