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Can
Modal verb can has the following meanings:
1) mental or physical ability to do something:
She can swim very well.
2) permission:
You can stay here if you want.
Can I have another ice-cream?
3) request:
Can you tell me the time?
Could expresses more polite request.
Could you show me the way to the bus station?
4) prohibition:
You can’t cross the street here.
5) surprise or astonishment
How can you be so silly?
How could he have told you such lies?
Present
+ He can play football today.
- He can’t play football today
? Can he play football today?
Sometimes instead of can we can use to be able to.
+ He is able to play football today.
- He isn’t able to play football today.
? Is he able to play football today?
Past
+ He could play football yesterday.
-He couldn’t play football yesterday.
? Could he play football yesterday?
Or
+ He was able to play football yesterday.
- He wasn’t able to play football yesterday.
? Was he able to play football yesterday?
Future
+ He will able to play football tomorrow.
- He won’t able to play football tomorrow.
? Will he able to play football tomorrow?
Modal verb can is used with different forms of infinitive to express doubt or astonishment.
Can she know English? Невже вона знає англійську?
Can she be working now? Невже вона зараз працює?
Can she have said it? Невже вона це сказала?
Can she have been working so long? Невже вона так довго працює?
Modal verb can is used with different forms of infinitive to express incredulity or improbability.
He can’t know English. Не може бути, щоб він знав англійську.
He can’t be working now. Не може бути, щоб він працював зараз.
He can’t have said it. Не може бути, щоб він сказав це.
He can’t have been working so long.Не може бути, щоб він працював так довго.
Could is normally used to say that somebody had the general ability to do something:
When he was young, he could dance well.
But if you mean that someone managed to do something in one particular situation, you have to use was/were able to (not could):
The fire spread quickly but everyone was able to escape.
The negative could is possible in all situations:
Kick couldn't swim at the age of 12. They couldn't get ashore.
The form could is used in the following ways:
1) in past-time contexts as the form of the indicative mood with indication of time:
Me could speak English when he was a child.
2) in present-time contexts to express unreality or as a milder and more polite form of can or as a form implying more uncertainty than can:
He could speak English if necessary.
Could I help you?
Could it be true?
3) to talk about possible future actions or happenings, especially when you make suggestions:
What shall we do this evening?
We could go to the cinema.
Can is also possible in this situation, but could is more unsure than can.
The past of could (+ simple infinitive) is could (+ perfect infinitive). You use could (+ perfect infinitive) to say that you had the ability or possibility to do something but you did not do it:
We could have gone for a walk but we decided to stay at home.
MAY/MIGHT
May has two tense forms: may (present) and might (past (in reported speech)):
The form might is used in two ways:
1) in past-time contexts, mainly in reported speech, in accordance with the rules of the sequence of tenses:
He told me that it might be true.
2) in present-time contexts as a milder and more polite form of may or as a form implying more uncertainty than may:
Might I come and see you?
or to express unreality (only-with the Perfect Infinitive)
He might have fallen ill i f he hadn't taken the pills.
May has the following meanings:
1) supposition implying uncertainty
He may be busy getting ready for his trip.
You may replace this may by modal words perhaps, maybe. May in соmbination with the Simple Infinitive usually refers the action to the future.
He may come soon.
The action can also refer to the present but only with the verbs that are not used in the continuous form:
He may be ill.
He may not know about it.
He may be sleeping. (Continuous Infinitive refers to the present)
In the meaning of supposition implying more uncertainty the form might is also used to express future or present action:
He might come soon. I le might be ill.
He might be doing his lessons now.
He might have spoken to her yesterday.
2) possibility due to circumstances:
You may order a taxi by telephone.,
Might followed by the Perfect Infinitive indicates that the action was not carried
out owing to certain circumstances.
You are so careless. You might have broken the cup!
3) permission:
-You may smoke here.
-May I smoke here?.
-You may not smoke here.
But it is more common lo use can or must lo express prohibition. To express permission the equivalent to be allowed to can be used:
Are we allowed to use a dictionary?
\
4) disapproval, reproach:
You might carry the parcel for me. You mighl have helped me!
Might expresses unreality only in combination wilh the Perfect Infinitive
There was a car accident in front of our house. Luckily Tommy was at school. He might have been killed.
CANAND MAYCOM PARED
The use of can and may is parallel only in two meanings:
1) possibility due to circumstances. May refers only to present and future, might is used in reported speech.
He may find the book in the library.
He can find the book in the library.
Both could and might + Perfect Infinitive mean that the action was not carricd out.
He might have found the book in ihe library.
He could have found the book in the library.
2) permission
In this meaning may is more official.
May (might) I speak to you for a moment, professor?
Can I have a cup of tea. mother?
May in prohibition is not common.
MUST
The modal verb must has one form. It is used in present-time contexts with reference to the present and future.
Must has the following meanings:
1) obligation (from the speaker's point of view)
You must talk to your daughter about her future.
2) prohibition
He must not leave his room for a while.
3) emphatic advice
You must come and see us when you are in London.
4) supposition implying strong probability
It must be late as the streets are deserted.
Where is he? - Me must be reading a book.
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