The negative form of used to is use to followed by an infinitive: I didn't use to smoke.
Habitual aspect
- ✅ I walk to work every day. — present simple (current habit)
- ✅ I used to smoke. — past habit, no longer true
- ✅ Every summer we would go to the lake. — repeated past action
- ❌ I would live in Paris. — wrong (would for habitual needs an action, not a state)
The habitual aspect marks actions as repeated/routine: present simple (now), used to (past, stopped), would (past repeated actions within a time frame).
Rule: used to works for both states and actions. Would works only for repeated actions — never states (I used to know him ✅, not I would know him ❌).
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.