Can and could are modal verbs. They are used to talk about ability, possibility, requests, and permission.
1. Ability
Can = ability in the present.
- I can swim.
- She can speak English.
Could = ability in the past.
- When I was young, I could swim very fast.
- He could play the piano at the age of five.
2. Requests
We use can and could to ask for something.
- Can you help me?
- Could you help me?
Could is more polite than can.
3. Permission
Can is commonly used to give or ask for permission.
- Can I leave early today?
- Yes, you can.
Could can also be used to ask permission politely.
- Could I use your phone?
4. Possibility
Can expresses a general possibility.
- It can be very cold in winter.
Could expresses a possible situation in the future.
- It could rain tomorrow.
- We could go to the beach this weekend.
Summary
| Can | Could |
|---|---|
| Present ability | Past ability |
| Informal requests | Polite requests |
| Permission | Polite permission |
| General possibility | Future possibility |
Tip: Use can for present situations and could for past ability or more polite requests.