Theory
Start point.
Can/could
· We will get wealthy people from the mainland who can afford second homes. (=General ability)
· Before the bridge was built we could only get to the island by ferry. (=General ability in the past)
May/could/might
· Up to 100,000 people may experience delays. (=It’s possible this will happen)
· Air passengers could be hit badly today. (=It’s possible)
· It might be a number of months before the sports centre is back in operation. (=It’s possible this is true; less certain than may or could)
Will/would
· That will push up the house price. (=Prediction about future)
· If schools highlighted the importance of physical exercise, this would have a major positive impact on children’s attitudes to sport. (=Prediction about an imaginary situation)
Must
· The cabin staff must accept the new working conditions. (= A rule or order)
· This negative attitude to sport mustn’t be allowed to continue. (=It’s not allowed or not a good idea)
Don’t need to/needn’t/don’t
· Parents don’t need to be interested in sport themselves. (=Its not necessarily true)
· I’m sure I don’t have to spell out the chaos being caused in the airline industry. (=It’s not necessarily true)
1 can, could, be able to: ability
We can use be able instead of can or could, particularly in more formal context:
The hotels on the islands are able to accommodate hundreds of visitors. Or
The hotels on the island can accommodate… (Less formal)
We use be able to talk about ability on specific occasion in the past:
Firefighters were able to bring the fire under control fairly quickly. (Not firefighter could bring…)
We can use either could or could or be able to in negatives in the past:
They couldn’t / weren’t able to prevent the fire damaging the school’s sport centre.
We usually prefer can or could with verbs of sense and verbs of thinking:
I can’t believe Mr Wade is being so confrontational.
We use be able to in perfect tenses, -ing forms, infinitives, and after modal verbs:
We’ve now been able to contact him.
The film star hates not being able to leave her house.
They’ve got to be able to adapt to change.
Parents might be able to help.
We prefer can and could in passives:
The news can be read on our website.
To talk about a future ability, we use will able to:
Islander won’t be able to buy properties.
2 may, might, can, could: possibility
To talk about more general possibility of something happening we can use can or may:
The temperature in the mountains can/may fall bellow freezing even at this time of the year.
We use could to say that something was possible in the past:
It could be a very rough journey, too.
We don’t use may to ask questions about possibility of something happening. Instead we use could or the phrase be likely to:
Could the negotiation finish today, do you think?
What time is the meeting likely to finish?
Might is sometimes used in questions, but is rather formal.
3 will, would, used to: conclusions, willingness, habitual events
We can use will to draw conclusions or state assumptions about things we think are true:
No doubt you will have heard the news by now.
We use will (not) to talk about (un) willingness or refusal to do something:
The minister says he will resign if no solution is found.
We will not be bullied by management.
The computer won’t let me print documents.
We use would to talk about willingness in the future, in conditionals, and when we say that we are willing but unable to do something:
Many people would be happy to pay higher taxes for better public services
! We don’t use would to talk about willingness on a specific occasion in the past:
David Wade agreed to meet the union representatives. (Not David Wade would agree…)
4 must, have (got) to: necessity, deduction
We can use either must or have to say that it is necessary to do something although have to is less formal and is also preferred in questions:
School must/ have to play a more active role in encouraging children to take up sports.
When we say that something was necessary in the past we used had to, not must:
Up to 200 teachers and pupils had to be evacuated from school in south wales today.
To say something is necessary in the future we use will have to:
To stay in business we will have to cut our costs.
We use must when we decide for ourselves that something is necessary or important:
I must give you my email address.
Have to suggest that someone else or an outside circumstance or authority make something necessary:
The council has to close two city centre car parks following a health and safety report.
We usually use must, rather than have to, when we conclude that something (has) happened or that something is true:
The bridge must have cost a fortune.
In negative conclusions we use can’t or couldn’t:
That can’t be right, surely? (Not that mustn’t be right surely?)
Some times we can use either have to or have got to, although have got to is more informal.
We use have to with frequency adverbs and with other modal verbs:
Islanders normally have to queue for half an hour to get on the ferry.
The airlines will a=have to return to the negotiating table.
If have is contracted (e.g. I’ve), then we must include got:
They’ve got to be changed (Not they’ve to be changed).
5 didn’t need to, didn’t have to, and needn’t have: not necessary
To say it was not necessary to do something in the past, we use didn’t need to or didn’t have to:
He didn’t have to wait long for a response (= he didn’t actually wait long)
To show that we think something that was done was not necessary, we used need to (needn’t) have:
The event organizers expected the bad weather to affect ticket sales. However, they need not have worried, as every ticket was sold. (=They worried but it was not necessary)
6 should, ought to: obligation
We can often use either should or ought to to talk about obligation (in giving advice and recommendations, saying what we think is a good idea and talking about responsibility):
I think we ought to/should keep Borland for the islanders! (=It’s a good idea or I recommend this)
We can use either should or ought to to say that something is likely because we have planned it or expect it to happen:
The contractors say the road will take five years to complete but they should/ ought to be able finish faster.
Can/could
· We will get wealthy people from the mainland who can afford second homes. (=General ability)
· Before the bridge was built we could only get to the island by ferry. (=General ability in the past)
May/could/might
· Up to 100,000 people may experience delays. (=It’s possible this will happen)
· Air passengers could be hit badly today. (=It’s possible)
· It might be a number of months before the sports centre is back in operation. (=It’s possible this is true; less certain than may or could)
Will/would
· That will push up the house price. (=Prediction about future)
· If schools highlighted the importance of physical exercise, this would have a major positive impact on children’s attitudes to sport. (=Prediction about an imaginary situation)
Must
· The cabin staff must accept the new working conditions. (= A rule or order)
· This negative attitude to sport mustn’t be allowed to continue. (=It’s not allowed or not a good idea)
Don’t need to/needn’t/don’t
· Parents don’t need to be interested in sport themselves. (=Its not necessarily true)
· I’m sure I don’t have to spell out the chaos being caused in the airline industry. (=It’s not necessarily true)
1 can, could, be able to: ability
We can use be able instead of can or could, particularly in more formal context:
The hotels on the islands are able to accommodate hundreds of visitors. Or
The hotels on the island can accommodate… (Less formal)
We use be able to talk about ability on specific occasion in the past:
Firefighters were able to bring the fire under control fairly quickly. (Not firefighter could bring…)
We can use either could or could or be able to in negatives in the past:
They couldn’t / weren’t able to prevent the fire damaging the school’s sport centre.
We usually prefer can or could with verbs of sense and verbs of thinking:
I can’t believe Mr Wade is being so confrontational.
We use be able to in perfect tenses, -ing forms, infinitives, and after modal verbs:
We’ve now been able to contact him.
The film star hates not being able to leave her house.
They’ve got to be able to adapt to change.
Parents might be able to help.
We prefer can and could in passives:
The news can be read on our website.
To talk about a future ability, we use will able to:
Islander won’t be able to buy properties.
2 may, might, can, could: possibility
To talk about more general possibility of something happening we can use can or may:
The temperature in the mountains can/may fall bellow freezing even at this time of the year.
We use could to say that something was possible in the past:
It could be a very rough journey, too.
We don’t use may to ask questions about possibility of something happening. Instead we use could or the phrase be likely to:
Could the negotiation finish today, do you think?
What time is the meeting likely to finish?
Might is sometimes used in questions, but is rather formal.
3 will, would, used to: conclusions, willingness, habitual events
We can use will to draw conclusions or state assumptions about things we think are true:
No doubt you will have heard the news by now.
We use will (not) to talk about (un) willingness or refusal to do something:
The minister says he will resign if no solution is found.
We will not be bullied by management.
The computer won’t let me print documents.
We use would to talk about willingness in the future, in conditionals, and when we say that we are willing but unable to do something:
Many people would be happy to pay higher taxes for better public services
! We don’t use would to talk about willingness on a specific occasion in the past:
David Wade agreed to meet the union representatives. (Not David Wade would agree…)
4 must, have (got) to: necessity, deduction
We can use either must or have to say that it is necessary to do something although have to is less formal and is also preferred in questions:
School must/ have to play a more active role in encouraging children to take up sports.
When we say that something was necessary in the past we used had to, not must:
Up to 200 teachers and pupils had to be evacuated from school in south wales today.
To say something is necessary in the future we use will have to:
To stay in business we will have to cut our costs.
We use must when we decide for ourselves that something is necessary or important:
I must give you my email address.
Have to suggest that someone else or an outside circumstance or authority make something necessary:
The council has to close two city centre car parks following a health and safety report.
We usually use must, rather than have to, when we conclude that something (has) happened or that something is true:
The bridge must have cost a fortune.
In negative conclusions we use can’t or couldn’t:
That can’t be right, surely? (Not that mustn’t be right surely?)
Some times we can use either have to or have got to, although have got to is more informal.
We use have to with frequency adverbs and with other modal verbs:
Islanders normally have to queue for half an hour to get on the ferry.
The airlines will a=have to return to the negotiating table.
If have is contracted (e.g. I’ve), then we must include got:
They’ve got to be changed (Not they’ve to be changed).
5 didn’t need to, didn’t have to, and needn’t have: not necessary
To say it was not necessary to do something in the past, we use didn’t need to or didn’t have to:
He didn’t have to wait long for a response (= he didn’t actually wait long)
To show that we think something that was done was not necessary, we used need to (needn’t) have:
The event organizers expected the bad weather to affect ticket sales. However, they need not have worried, as every ticket was sold. (=They worried but it was not necessary)
6 should, ought to: obligation
We can often use either should or ought to to talk about obligation (in giving advice and recommendations, saying what we think is a good idea and talking about responsibility):
I think we ought to/should keep Borland for the islanders! (=It’s a good idea or I recommend this)
We can use either should or ought to to say that something is likely because we have planned it or expect it to happen:
The contractors say the road will take five years to complete but they should/ ought to be able finish faster.