1. used to express past ability or possibility
Usage: past tense of ‘can’
2. used to make polite requests or suggestions
Usage: more polite than ‘can’
3. used to express possibility or uncertainty in the present or future

Examples

• When I was younger, I could run five miles without stopping.
• Could you please pass the salt?
• It could rain later today.
• If I had more time, I could help you with your project.
• She could speak three languages fluently.
• Could we meet tomorrow instead?
• The package could arrive by Friday.
• I could have finished earlier if I had started sooner.