26. Can, could and (be) able to
We use can to say that something is possible or allowed, or that somebody has the ability to do something, We use can + infinitive (can do / can see etc.):
You can say that somebody is able to do something, but can is more usual
But can has only two forms: can(present) and could(past). So sometimes it is necessary to use (be) able to .Compare:
- I can’t sleep. ====== I haven’t been able to sleep recently.
- Tom can come tomorrow. ======= Tom might be able to come tomorrow.
Could
Sometimes could is the past of can. We use could especially with:
see hear smell taste feel remember understand
We had a lovely room in the hotel. We could see the lake.
We also use could to say that somebody had the general ability or permission to do something:
Could and was able to
We use could for general ability. But if you want to say that somebody did something in a specific stiuation, use was / were able to or managed to (not could)
The fire spread through the building very quickly, but fortunately everybody was able to escape / managed to escape. (not could escape)
We didn’t know where David was, but we managed to find / were able to find him in the end. (not could find)
Compare:
Jack was an excellent tennis player when he was younger. He could beat anybody. (= he had the general ability to beat anybody)
but
Jack and Andy played a match yesterday. Andy played well, but Jack managed to beat him. (= he managed to beat him this time)
The negative couldn’t (could not) is possible in all situations”
27. Could (do) and could have (done)
We use could in number of ways. Sometimes could is the past of can (see Unit 26):
But could is not only used in this way. We also use could to talk about possible actions now or in the future (especially to make suggestions. For example):
- What shall we do tonight? We could go to the cinema.
- Whe you go to Paris next mouth, you could stay with Sarah. Yes, I suppose I could.
Can is also possible in these sentences (‘We can go to the cinema’. etc) Could is less sure than can
We also use could (not can) for actions that are not realistic. For example:
I’m so tired, I could sleep for a week. (not I can sleep for a week)
Compare can and could:
- I can stay with Sarah when I go to Paris. (realistic)
- Maybe I could stay with Sarah when I go to Paris. (possible, but less sure)
- This is a wonderful place. I could stay here for ever. (unrealistic)
We also use could (not can) to say that something (a situation or a happening) is possible now or in the future. The meaning is similar to might or may (see Unit 29):
- The story could be ture, but I don’t think it is. (not can be ture)
- I don’t know what time Lisa is coming. She could get here at any time
Compare can and could:
- The weather can change very quickly in the mountains. (in general)
- The weather is nice now, but it could change. (the weather now, not in general)
We use could have (done) to talk about the past. Compare:
- I’m so tired, I could sleep for a week. (not) ==== I was so tired, I could have slept for a week. (past)
- The situation is bad, but it could be worse. (now) ==== The situation was bad, but it could have been worse. (past)
Sometimes could have happened = it was possible but did not happen:
- Why did you stay at a hotel when you were in Paris? You could have stayed with Sarah. (you didn’t stay with her)
- David was lucky, He could have hurt himself when he fell, but he’s OK.
We use couldn’t to say that something would not be possible
For the past we use couldn’t have (done):
- We had a really good holiday. It couldn’t haven been better.
- The trip was cancelled last week. Paul couldn’t haven gone anyway because he was ill. (= it would not have been possible for him to go)
28. Must and can’t
You can use must to say that you believe something is certain:
‘Joe is a hard worker.’ ‘Joe? You must be joking. He doesn’t do anything’
You can use can’t to say that you believe something is not possible.
Study the structure:
I / you / he (etc.) | must / can’t | be (tired / hungry / at work etc.) |
I / you / he (etc.) | must / can’t | be (doing / going / joking etc.) |
I / you / he (etc.) | must / can’t | do / get / know / have etc. |
For the past we use must have(done) and can’t have (done)
- ‘We used to live very near the motorway’ ‘Did you ? It must have been noisy.’
- ‘I’ve lost one of my gloves.’ ‘You must have got my message’
- Tom walked into a wall. He can’t have been looking where he was going.
Study the structure.
I / you / he(etc) | must / can’t | have | been (asleep / at work etc.) |
I / you / he(etc) | must / can’t | have | been (doing / looking etc.) |
I / you / he(etc) | must / can’t | have | gone / got / known etc. |
You can use couldn’t have instead of can’t have
- Sarah couldn’t have got my message.
- Tom couldnt have been looking where he was going
29. May and might 1
We use may or might to say that something is possible. Usually you can use may or might, so you can say:
It may be true. or It might be true.
She might know. or She may know.
Study the structure.
I / you / he(etc) | may / might | (not) | be (true / in his office etc.) |
I / you / he(etc) | may / might | (not) | be (doing / working / having etc.) |
I / you / he(etc) | may / might | (not) | know / work / want etc. |
For the past we use may have (done) or might have (done)
Study the structure.
I / you / he(etc) | may / might | (not) have | be (asleep / at home etc.) |
I / you / he(etc) | may / might | (not) have | be (doing / working / geeling etc.) |
I / you / he(etc) | may / might | (not) have | known / had / wanted / left etc. |
Could is similar to may and might
It’s a strange story, but it could be true. (= It is possible that it’s true)
But couldn’t (negative) is different from may not and might not. Compare:
Sarah couldn’t have got my message. Otherwise she would have relied. (= it is not possible that she got my message)
I wonder why Sarah hasn’t replied to my message. I suppose she might not have got it. (= It’s possible that she didn’t get it - so perhaps she did, perhaps she didn’t)
30. May and might 2
We use may and might to talk about possible actions or happenings in the future.
- I haven’t decided yet where to go on holiday. I may go to Ireland. (= perhaps I will go there)
- Take an unbrella with you . It might rain later. (= perhaps it will rain)
- The bus isn’t always on time. We might have to wait a few minutes. (= perhaps we will have to wait)
Compare will and may / might
- I’ll be late this evening (for sure)
- I may / might be late this evening
Usually you can use may or might
But we use only might (not may) when the situation is not real.
If they paid me better, I might work harder. (not I may work)
The situation here is not real because they do not pay me well, so I’m not going to work hard.
There is a continuous form: may / might be -ing. Compare this with will be -ing
- Don’t phone at 8.30 I’ll be watching the football on television
- Don’t phone at 8.30 I might be watching (or I may be watching) the football on TV. (= perhaps I’ll be watching it)
We also use may / might be -ing for possible plans. Compare:
- I’m going to Ireland in July. (for sure)
- I might be going (or I may be going) to Ireland soon. (possible)
But you can also say ‘I might go / I may go …’ with little difference in meaning
Might as well
We might as well do something = We should do it because there is not better alternative. There is no reason not to do it.
May as well is also possible
31. Have to and must
I have to do something = it is necessary to do it, I am obliged to do it.
You can’t turn right here. You have to turn left.
We use do / does / did in questions and negative sentences (for the present and past simple):
You can say I’ll have to …, I’m going to have to … and I might / I may have to..
- They can’t fix my computer, so I’ll have to buy a new one. or I’m going to have to buy a new one.
- Tom might have to work late womorrow. or Tom may have to work… (= it’s possible that he will have to)
You can use must or have to to give your own opinion (for example, to say what you think is necessary, or to recommend someone to do something):
We use have to (not usually must) to say wjat someone is obliged to do. The speaker is not giving his / her own opinion
But must is used in written rules and instructions
You cannot use must to talk about the past
You can use have got to instead of have to.
- I’ve got to work tomorrow or I have to work tomorrow
- When has Helen got to go ? or When does Helen have to go?
32. Must mustn’t needn’t
Msut and mustn’t
You must do something = it is necessary that you do it
You mustn’t do something = it is necessary that you do not do it (so don’t do it)
Needn’t and don’t need to
You needn’t do something = it’s not necessary to do it (but you can if you like)
- We’ve got plenty of time. We needn’t hurry. (= it is not necessary to hurry)
- Joe can stay here. He needn’t come with us. (= it is not necessary for him to come)
You can also use don’t / doesn’t need to:
- We don’t need to hurry
Remember that we say don’t need to do / doesn’t need to do, but needn’t do (without to)
Needn’t have (done)
They needn’t have reserved a table. = They reserved a table, but this was not necessary.
Compare needn’t (do) and needn’t have (done)
- Everything will be OK. You needn’t worry. (it is not necessary)
- Everything was OK. You needn’t have worried. (you worried, but it was not necessary)
Needn’t have (done) and didn’t need to (do)
He needn’t have done something = he did it, but now we know that it was not necessary
He didn’t need to do something = it was not necessary to do it. It doesn’t matter whether he did it or not
- He didn’t need to get up early, so he didn’t
- He didn’t need to get up early, but it was a neautiful morning, so he did.
He didn’t have to … is also possible in these examples.
33. Should 1
You should do something = it is a good thing to do or the right thing to do. You can use should to give advice or to give an opinion
We often use should with I think / I don’t think / Do you think …?
I think the government should do more to imporve education
I don’t think you should work so hard
‘Do you think I should apply for this job?’ ‘Yes, I think you should’
You shouldn’t do something = it isn’t a good thing to do
Should is not as strong as must or have to.
You can use should when something is not right or what you expect:
Where’s Tina? She should be here by now. (= she isn’t here yet, and this is not normal)
We also use should to say that we expect something to happen:
Helen has been studying hard for the exam, so she should pass. (= I expect her to pass)
You should have done something = you didn’t do it, but it would have been the right thing to do.
You missed a great party last night. You should have come. Why didn’t you ?
You shouldn’t have done something = you did it, but it was the wrong thing to do:
I’m feeling sick. I shouldn’t have eaten so much. (= I ate too much)
Compare should (do) and should have (done)
- You look tired. You should go to bed now.
- You went to bed very late last night. You should have gone to bed earlieer.
Ought to
You can use ought to instead of should in the sentences on this page. We say ‘ought to do’ (with to)
Do you think I ought to apply for this job? (= Do you think I should apply …?)
34. Should 2
You can use should after
insist | recommend | suggest | demand | propose |
I insisted that he should apologise.
Doctors recomment that everyone should eat plenty of fruit
also
It’s important / vital / necessary / essential that … should …:
It’s essential that everyone should be here on time.
You can also leave out should in the sentences in section A.
It’s essential that everyone be here on time. (= … that everyone should be here)
I insisted that he apologise. (= … that he should apologise)
This form (be / do / apologise etc.) is called the subjunctive. It is the same as the infinitive (without to). You can also use normal present and past tenses.
It’s essential that everyone is here on time.
I insisted that he apologised
After suggest, you cannot use to … (‘to do / to buy’ etc.).
What do you suggest we should do.
What do you suggest we do? (but not what do you suggest us to do?)
I suggedted that she should buy a car with the money she’d won
I suggedted that she buy a car.
I suggedted that she bought a car. (but not I suggested her to buy)
You can also use -ing after suggest (What do you suggest doing?). See Unit 53
You can use should after a number of adjectives, especially:
strange | odd | funny | typical | natural | interesting | surprised | surprising |
You can say ‘If something should happen …’. For example
We have no jobs at present, but if the situation should change, we will contact you
You can also begin with should (Should something happen)
Should the situation change, we will contact you
This means the same as ‘If the situation changes,…’. With should, the speaker feels that the possibility is smaller
You can use I should … / I shouldn’t to give somebody advice. For example.
Shall I leave now? ===== No, I should wait a bit
Here, I should wait = I wouldwait if I were youm U advuse you to wait.
35. Had better It’s time…
Had better (I’d better / you’d better etc.)
I’d better do something = it is advisable to do it. If I don’t do it, there will be a problemor a danger.
I have to meet Amy in ten minutes. I’d better go now or I’ll be late.
The negative is I’d better not (= I had better not)
The jacket looks good on you. Are you going to buy it? ======= I’d better not. It’s too expensive
Remember that:
- The form is ‘had better’ (usually ‘I’d better / you’d better’ etc. in spoken English)
- Had is normally past but the meaning of had better is present or future, not past
- We say ‘I’d better do’ (not to do)
Had better and should
Had better is similar to should, but not exactly the same. We use had better only for a specific situation, not for things in general. You can use should in all types of situations to give an opinion or give advice.
- It’s late. You’d better go. / You should go. (a specific situation)
- You’re always at home. You should go out more often. (in general - not ‘had better go’)
Also, with had better, there is always a danger or a problem if you don’t follow the advice.
Should means only ‘it is a good thing to do’.
It’s time
You can say It’s time (for somebody) to …:
It’s time to go home. / It’s time for us to go home.
But you can also say:
It’s late. It’s time we went home.
When we use it’s time + past (we went / I did / they were etc.), the meaning is present, not past
It’s time somebody did something = they should have already done it or started it. We often use this structure to criticise or to complain.
- This situation can’t continue. It’s time you did something about it.
- He’s very selfish. It’s time he realised that he isn’t the most important person in the world.
You can also say It’s about time …. This makes the criticism stronger.
Jack is a great talker. But it’s about time he did something instead of just talking
36. Would
We use would (‘d) / wouldn’t when we imagine a situation or action (= we think of something that us not real)
- It would be nice to buy a new car, but we can’t afford it.
- I’d love to live by the sea.
We use would have (done) when we imangine situations or actions in the past (= things that didn’t happen)
They helped us a lot. I don’t know what we’d have done
Compare would (do) and would have (done):
- I would call Lisa, but I don’t have her number. (now) ==== I would have called Lisa, but I didn’t have her number. (past)
- I’m not going to invite them to the party, They wouldn’t come anyway. ==== I didn’t invite them to the party, They wouldn’thave come anyway.
We often use would in sentences with if (see Units 38 - 40)
I would call Lisa if I had her number.
I would have called Lisa if I’d had her number.
Compare will (‘ll) and would (‘d)
I’ll stay a little longer. I’ve got plenty of time. ==== I’d stay a little longer, but I really have to go now. (so I can’t stay longer)
I’ll call Lisa. I have her number. ==== I’d call Lisa, but I don’t have her number. (so I can’t call her)
Sometimes would / wouldn’t is the past of will / won’t.
I’ll call you on Sunday. ==== Tom said he’d call me on Sunday
Somebody wouldn’t do something = he / she refused to do it.
You can also use would to talk about things that happened regularly in the past
With this meaning, would is similar to used to (see Unit 18)
37. Can / Could / Would you …? etc. (Request, offers, permission and invitations)
Asking people to do things (requests)
We use can or could to ask people to do things.
Note that we say Do you think you could …? (not can)
Do you think you could …? (not can)
We also use will and would to ask people to do things (but can / could are more usual):
Asking for things
To ask for something, we use Can I have …? / Could I have …? or Can I get …?
May I have …? is also possible.
Asking to do things
To ask to do something, we use can, could, or may
May is more formal than can or could
To ask to do something, you can also say Do you mind if I …? or Is it all right / Is it OK if I …?
- Do you mind if I use your phone?
- Is it all right if I come in?
Offering to do things
To offer to do something, we use Can I…?
To offer or invite, we use Would you like ,,,? (not Do you like):
- Would you like a cup of coffee?
- Would you like to eat with us tonight?
I’d like … is a polite way of saying what you want:
- (at a tourist information office) I’d like some information about hotels, please.
- (in a shop) I’d like to try on this jacket, please.