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.

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).

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.

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.

Idiom

• It's raining cats and dogs. — means "raining heavily" (not literal animals)
• Break a leg! — means "good luck" (not an injury wish)
• Spill the beans — means "reveal a secret"
• Kick the bucket — means "to die" (no actual bucket involved)

Idioms are fixed phrases whose meaning can't be guessed from the individual words. They must be memorised as complete units — word-by-word translation from another language almost always fails.

Pattern: if a phrase is literally absurd but everyone uses it with a specific meaning → it's an idiom. Learn it as a chunk, not as individual words.

C1 | Advanced

• ✅ Not only did she finish early, but she also helped others. — inversion for emphasis
• ✅ It is the process that matters, not the result. — cleft sentence
• ✅ I insist that he be present. — formal subjunctive
• ✅ Were I to disagree, I would say so. — inverted conditional

These are C1 structures — the CEFR advanced level. At C1 you control inversion, cleft sentences, subjunctive forms, and register-switching fluently across formal and informal contexts.

Marker: if you can restructure a sentence for rhetorical effect without hesitation, you're C1.

Hard

• Had she not intervened, the situation would have escalated. — inverted conditional
• All distractors are grammatically plausible in other contexts
• Multiple rules interact (e.g., tense + aspect + modality)
• Context determines the answer — no single "rule" is enough

Hard marks upper-intermediate to advanced challenges: B2+, interacting rules, edge cases, plausible distractors, and contexts where pattern-matching fails.

Use "Hard" when Easy/Medium feel trivial and you want to test whether you actually understand a rule versus just recognising surface patterns.