Can is used to talk about 3 things:
- We use can to talk about things that we are able to do in the present time:
- I can help you with your project if you want
- Look mum, I can swim!
- We can also use be able to for very specific situations:
- If I am able to finish the report tonight I will let you know
- We use can to ask permission for something
- Can I join in the game with you?
- Can I open the window?
- This form of asking permission is used for friends and people we know well, if we want to be more polite we must use could or may:
- May I take a look at the menu?
- Could I take next week off for a holiday?
- We also use can when we are talking about things which are allowed and not allowed. We call this reporting permission. We use can to talk about things which are allowed in the present time or the future:
- If you have a voucher then you can get in for free.
- If I pass this exam then I can drive a truck.
- We can also use be allowed to for specific situations:
- I'm not sure if we are allowed to sit here
- To talk about something which is possible, we only use can to talk about GENERAL POSSIBILITY, NOT SPECIFIC SITUATIONS
- In the summer, temperatures can reach 40 degrees here (general fact about something that is possible)
- A tornado can reach speeds of up to 25 miles per hour (general fact about something that is possible)
- To talk about the possibility of specific events happening in the future, we use could. Compare the sentences below with the sentences above:
- The weather forecast says that temperatures could reach 40 degrees tomorrow (specific event tomorrow)
- Hurricane Elsa could reach speeds of up to 150 miles per hour later (specific event later)
Not sure if you need to use 'can' or 'could'
Try this diagram to help you:
Or try our quiz to help you find which one you want: