English Grammar Secrets

Could

'Could' can be used to talk about the past, the present or the future.

'Could' is a past form of 'can'

• When I was living in Boston, I could walk to work.
• He phoned to say he couldn't come.
• I could see him clearly but I couldn't hear him and then the videoconference line went dead.

'Could' is used to make polite requests. We can also use 'can' for these but 'could' is more polite.

• Could you help me, please?
• Could you lend me some money?
• Could I have a lift?
• Could I bother you for a moment?

If we use 'could' in reply to these requests, it suggests that we do not really want to do it. If you agree to the request, it is better to say 'can'.

• Of course I can.
• I could help you if it's really necessary but I'm really busy right now.
• I could lend you some money but I'd need it back tomorrow without fail.
• I could give you a lift as far as Birmingham.

'Could' is used to talk about theoretical possibility and is similar in meaning to 'might'.

• It could rain later. Take an umbrella.
• He could be there by now.
• Could he be any happier?
• It could be Sarah's.

exercise 1

exercise 2                                                                                                                          exercise 3                                                                                                                                                                  exercise 4                                                                                                                                                                    Return to List of Grammar Lessons

English Grammar Secrets

Can

We use 'can' to talk about 'possibility'.

• Can you do that?
• I can't manage to do that.
• You can leave your car in that parking space.
• You cannot smoke in here.

Notice that there are two negative forms: 'can't' and 'cannot'. These mean exactly the same thing. When we are speaking, we usually say 'can't'.

We use 'can' to talk about 'ability'.

• I can speak French.
• I can't drive.

We use 'can' to ask for and give permission. (We also use 'may' for this but is more formal and much less common.)

• Can I speak to you or are you too busy?
• You can use my phone.
• You can't come in.

We use 'can' in offers, requests and instructions.

• Can I help?
• Can you give me a hand?
• When you finish that, you can take out the garbage.

We use 'can' with 'see' 'hear' 'feel' 'smell' 'taste' to talk about something which is happening now . (Where you would use the present continuous with most other verbs.)

• I can smell something burning.
• Can you hear that noise?
• I can't see anything.

We can use 'can't' for deduction. The opposite of 'can't' in this context is 'must'.

• You can't be hungry. You've just eaten.
• You must be hungry. You haven't eaten anything all day.
• He was in London one hour ago when I spoke to him. He can't be here yet.

exercise 1

exercise 2                                                                                                                                   exercise 3                                                                                                                                                                  exercise 4                                                                                                                                                                       exercise 5                                                                                                                                                                  exercise 6

Return to List of Grammar Lessons