Forms
Basecould
Negativecould not
Contractedcouldn't
Past form(historical: could)
Past negativecould not have
Past contractedcouldn't have
Question patternCould I / you / he …?
Meanings & usage
- Past ability: “She could run 10km in her twenties.” General past capability
- Polite request: “Could you pass the salt?” More polite than 'can'
- Hypothetical: “I could help if I had time.” Imagined / conditional
- Past speculation: “He could have told us.” Missed opportunity
- Polite suggestion: “You could try the new café.” Soft recommendation
Tense patterns
How this modal combines with a base verb across time references. The modal itself doesn’t conjugate; the time meaning comes from what you attach.
Reference
Affirmative
Negative
Question
Hypothetical
I could work there
I couldn't work there
Could I work there?
Past ability
She could swim at five
She couldn't swim
Could she swim?
Perfect (regret)
I could have gone
I couldn't have gone
Could I have gone?
Continuous
I could be working
I couldn't be working
Could you be working?
Common mistakes
For specific past ability (one event), use was/were able to, not could: "He was able to escape" ✓ vs "He could escape" ✗. Could works for general past ability only.