Apostrophe

• ✅ the dog's bone (possession) — ❌ the dog's are barking (wrong — plural, no apostrophe)
• ✅ it's raining (= it is) — ❌ the cat licked it's paw (wrong — possessive its has no apostrophe)
• ✅ don't, they're, we'll (contractions) — ❌ apple's for sale (wrong — plain plural)
• ✅ James's book or James' book — both accepted for names ending in s

The apostrophe ( ' ) marks either possession (the eagle's feathers) or missing letters in contractions (do not → don't). It never makes a plural.

Rule: if you mean "belongs to," add 's. If you're shortening two words into one, apostrophe replaces the missing letters. Otherwise — no apostrophe.

Future tense

• ✅ I*'ll** help you.* — spontaneous decision (will)
• ✅ I*'m going to** study medicine.* — planned intention
• ✅ I*'m meeting** Sam at six.* — fixed arrangement (present continuous)
• ✅ The train leaves at 8. — scheduled event (present simple)

English has no single future tense — it uses will, be going to, present continuous, and present simple for different shades of future meaning. The choice signals whether you're predicting, planning, arranging, or stating a schedule.

Pattern: spontaneous → will. Planned → going to. Arranged → present continuous. Timetabled → present simple.

Gerund

• ✅ I enjoy reading. — ❌ I enjoy to read.
• ✅ She's good at swimming. — ❌ She's good at to swim.
• ✅ He avoids making eye contact. — gerund after avoid
• ✅ Running is good exercise. — gerund as subject

A gerund is the -ing form of a verb functioning as a noun. It follows verbs like enjoy, avoid, finish, mind and ALL prepositions. Never use an infinitive where a gerund is required.

Rule: after a preposition (at, in, of, about, without) → always gerund. After enjoy, avoid, finish, mind, suggest, deny → always gerund.

Infinitive

• ✅ I want to go. — to-infinitive after want
• ✅ She can swim. — bare infinitive after modal
• ✅ Let me help. — bare infinitive after let
• ❌ I enjoy to read. — wrong (enjoy takes gerund, not infinitive)

The infinitive has two forms: to-infinitive (to go) after verbs like want, decide, plan, hope; bare infinitive (go) after modals and causatives (let, make, help).

Rule: after want, need, decide, plan, hope, expect, agree, refuse → to-infinitive. After can, will, must, let, make → bare infinitive. After enjoy, avoid, finish → gerund, NOT infinitive.

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).

Phrase

• the red car — noun phrase (functions as one noun unit)
• on the table — prepositional phrase
• has been running — verb phrase
• very quickly — adverb phrase

A phrase is a group of words that functions as a single unit WITHOUT a subject + verb pair. Types: noun phrase, verb phrase, prepositional phrase, adjective phrase, adverb phrase.

Key distinction: a phrase lacks a subject-verb pair. If it has subject + verb → it's a clause, not a phrase. Phrases are the building blocks clauses are made of.

Present tense

• I work here. — simple present (habit/permanent)
• I am working now. — present progressive (happening right now)
• I have lived here for 10 years. — present perfect (started past, still true)
• I have been waiting for an hour. — present perfect progressive (duration up to now)

Four present tense forms: simple (habits/facts), progressive (now/temporary), perfect (past → present relevance), perfect progressive (ongoing duration). Each encodes a different relationship between the action and the present moment.

Trap: "I am living here for 10 years" ❌ — started in the past + still true = present PERFECT (have lived/have been living), not progressive.

Questions

• ✅ Do you like coffee? — do-support (no existing auxiliary)
• ✅ Can she swim? — inversion (auxiliary before subject)
• ✅ Where does he live? — wh-question
• ✅ You're coming, aren't you? — tag question

Questions require inversion (auxiliary before subject) or do-support (add do/does/did). Types: yes/no (Do you…?), wh- (What/Where/When…?), negative (Don't you…?), tag (…isn't it?).

Rule: find the auxiliary. Move it before the subject. No auxiliary? Add do/does/did. Never use just intonation in written English (You like coffee? is not standard).

Sentence

• She left. — simple (one independent clause)
• She left, and he stayed. — compound (two independents)
• She left because she was tired. — complex (independent + dependent)
• She left because she was tired, and he stayed. — compound-complex

A sentence = one or more clauses forming a complete thought, ending with terminal punctuation. Four types based on clause structure: simple, compound, complex, compound-complex.

Minimum requirement: at least one independent clause with a subject + finite verb. Without that → fragment.

Verb

• walk → walk / walks / walked / walked / walking (5 forms, regular)
• go → go / goes / went / gone / going (5 forms, irregular)
• be → am/is/are/was/were/be/being/been (8 forms)
• can → can / could (modal: only 2 forms, no -s, no -ing)

A verb is the one word class every English sentence requires. Carries tense (when), aspect (duration), mood (attitude), and voice (active/passive). Regular verbs add -ed; ~200 irregular verbs have unpredictable past forms.

Key insight: fix your verbs and most grammar problems disappear. Wrong tense, wrong agreement, wrong form — verb errors account for the majority of grammatical mistakes.

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.

Simple tense

• ✅ I go to work every day. — present simple (habit)
• ✅ She went home yesterday. — past simple (completed action)
• ✅ I will call you later. — future simple (promise/decision)
• ✅ Water boils at 100°C. — present simple (general truth)

The simple aspect is the default, unmarked verb form. Present simple = habits, facts, schedules. Past simple = completed actions. Future simple = predictions, promises, decisions. No auxiliary needed (except will for future and do for questions/negatives).

Rule: if the action is a fact, habit, completed event, or scheduled future — and you don't need to emphasise it being in-progress or connected to now → simple tense.

Collocations

• ✅ make a decision — ❌ do a decision
• ✅ strong coffee — ❌ powerful coffee
• ✅ heavy rain — ❌ strong rain
• ✅ highly unlikely — ❌ very unlikely (grammatical, but less natural)

Collocations are word pairs that English habitually puts together. Both options may be grammatically valid, but one sounds native and the other doesn't.

Pattern: there's no logic to predict them — you make decisions but do homework, you have strong coffee but heavy rain. They must be learned as chunks, not deduced from rules.

A2 | Elementary | Pre-intermediate

• ✅ I went to the cinema yesterday. — past simple
• ✅ I have visited Paris twice. — present perfect (life experience)
• ✅ If it rains, I'll take an umbrella. — first conditional
• ✅ You should see a doctor. — modal for advice

These patterns are A2 — the second CEFR level. At A2 you move past survival phrases into real grammar: past tenses, the present perfect, basic conditionals, and modals for advice/obligation.

Marker: if you can describe yesterday and give simple advice, but struggle with abstractions or nuance, you're at A2.

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.