English Grammar Secrets

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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.
  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.

  
  
  

  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. 

  
  

  May / might

  may

  We can use 'may' to ask for permission. However this is rather formal and not used very often in modern spoken English

  • May I borrow your pen?
  • May we think about it?
  • May I go now?

  We use 'may' to suggest something is possible

  • It may rain later today.
  • I may not have time to do it today.
  • Pete may come with us

  might

  We use 'might' to suggest a small possibility of something. Often we read that 'might' suggests a smaller possibility that 'may', there is in fact little difference and 'might is more usual than 'may' in spoken English.

  • She might be at home by now but it's not sure at all.
  • It might rain this afternoon.
  • I might not have time to go to the shops for you.
  • I might not go.

  For the past, we use 'might have'.

  • He might have tried to call while I was out.
  • I might have dropped it in the street.

  
  

  Should

  We use 'should' for giving advice.

  • You should speak to him about it.
  • He should see a doctor.
  • We should ask a lawyer.

  We use 'should' to give an opinion or a recommendation.

  • He should resign now.
  • We should invest more in Asia.
  • They should do something about this terrible train service.

  'Should' expresses a personal opinion and is much weaker and more personal than 'must' or 'have to'. It is often introduced by ' I think'.

  • I think they should replace him.
  • I don't think they should keep the contract.
  • Do you think we should tell her.
     
    Should 2

    We can use 'should' after 'reporting verbs' such as
    demand  insist  propose  recommend  suggest

    • He demanded that we should pay for the repair.
    • She insisted that she should pay for the meal.
    • I have proposed that he should take charge of the organization.
    • The committee recommends that Jane should be appointed.
    • We have suggested that Michael should be given a reward for his hard work.

    However, it is also possible to say exactly the same thing by omitting the 'should' and just using the infinitive form without 'to' . Some people call this the 'subjunctive' form.

    • He demanded that we pay for the repair.
    • She insisted that she pay for the meal.
    • I have proposed that he take charge of the organization.
    • The committee recommends that Jane be appointed.
    • We have suggested that Michael be given a reward for his hard work.

    We can use 'should' after various adjectives. Typical examples are :
    funny  interesting  natural  odd  strange  surprised  surprising  typical

    • It's funny that you should say that. I was thinking exactly the same thing.
    • It's interesting that they should offer him the job. Not an obvious choice.
    • It's natural that you should be anxious. Nobody likes speaking in public.
    • Isn't it odd that he should be going to the same tiny hotel? What a coincidence.
    • It's strange that you should think so. Nobody else does.

    We can use 'should' in 'if clauses' when we believe that the possibility of something happening is small.

    • If you should happen to see him before I do, can you tell him that I want to speak to him urgently?
    • If there should be a problem, just give me a call and I'll sort it out.
    • If anyone should ask where I am, say I'm in a meeting.

    We use 'should' in various fixed expressions.
    To show strong agreement

    • They're paying you compensation?   I should think so.

    To express pleasure when you receive a gift

    • What a fantastic present. You really shouldn't have.

    To emphasize  a visible emotion

    • You should have seen the look on her face when she found out that she had got the promotion. 

    Must or have to

    We can use 'must' to show that we are certain something is true. We are making a logical deduction based upon some clear evidence or reason.

    • There's no heating on. You must be freezing.
    • You must be worried that she is so late coming home.
    • I can't remember what I did with it. I must be getting old.
    • It must be nice to live in Florida.

    We also use 'must' to express a strong obligation. When we use 'must' this usually means that some personal circumstance makes the obligation necessary (and the speaker almost certainly agrees with the obligation.)

    • I must go to bed earlier.
    • They must do something about it.
    • You must come and see us some time.
    • I must say, I don't think you were very nice to him.

    We can also use 'have to' to express a strong obligation. When we use 'have to' this usually means that some external circumstance makes the obligation necessary.

    • I have to arrive at work at 9 sharp. My boss is very strict.
    • We have to give him our answer today or lose out on the contract.
    • You have to pass your exams or the university will not accept you.
    • I have to send a report to Head Office every week.

    In British English, we often use 'have got to' to mean the same as 'have to'.

    • I've got to take this book back to the library or I'll get a fine.
    • We've got to finish now as somebody else needs this room.

    We can also use ' will have to' to talk about strong obligations. Like 'must' this usually means that that some personal circumstance makes the obligation necessary. (Remember that 'will' is often used to show 'willingness'.)

    • I'll have to speak to him.
    • We'll have to have lunch and catch up on all the gossip.
    • They'll have to do something about it.
    • I'll have to get back to you on that.

    As you can see, the differences between the present forms are sometimes very small and very subtle. However, there is a huge difference in the negative forms.

    • We use 'mustn't' to express strong obligations NOT to do something.
    • We mustn't talk about it. It's confidential.
    • I mustn't eat chocolate. It's bad for me.
    • You mustn't phone me at work. We aren't allowed personal calls.
    • They mustn't see us talking or they'll suspect something.

    We use 'don't have to' (or 'haven't got to' in British English) to state that there is NO obligation or necessity.

    • We don't have to get there on time. The boss is away today.
    • I don't have to listen to this. I'm leaving.
    • You don't have to come if you don't want to.
    • He doesn't have to sign anything if he doesn't want to at this stage.
    • I haven't got to go. Only if I want to

    
    

    
    

    Shall

    We don't use 'Shall' very frequently in modern English, particularly in American English.

    It is used to make offers and suggestions and to ask for advice.

    • What time shall we meet?
    • Shall we vote on it now?
    • What dress shall I wear?
    • Shall I open the window?

    You only really need to know that about 'shall' in modern English. Read the rest of this only if you want to know more about how some older speakers still use 'shall'.

    Formerly, in older grammar, 'shall' was used as an alternative to 'will' with 'I' and 'we'. Today, 'will' is normally used. When we do use 'shall', it has an idea of a more personal, subjective future.

    • I shall go to see the boss and I shall ask him to explain this decision.

    Notice that the negative of 'shall' can be 'shall not' or 'shan't' – though the second one is now very rare in American English.

    • I don't like these people and I shall not go to their party.
    • I shan't object if you go without me.