Grammar Point Explainer with Progressive Drills

Explain a grammar point in a target language and drill it with progressive exercises.Input: grammar point (e.g. preterite vs imperfect, conditionals, particles), target language, learner level.Structure:1. Rule in plain language - one sentence "when to use it", plus exceptions listed as bullet points. Include the visual pattern/form table if the language has morphology.2. Compare with the closest point it is often confused with (e.g. which tense pairs are commonly mixed) and give a one-line decision test.3. Drills in 3 tiers: - Tier 1 - Recognition: 5 sentences; say which form fits and why. - Tier 2 - Gap-fill: 5 sentences with the correct conjugation/particle required. - Tier 3 - Production: 3 open prompts (translate/say) using the point, plus one free-form sentence of the learner's own.4. Show the answers only after the learner attempts; give feedback that includes the rule again if wrong.5. Common-mistakes box: the 3 typical errors learners of this L1 make with this point, pre-emptively explained.Keep it tight; reuse the learner's level for examples.