Dave
15 lug 20215 min
Aggiornato il: 9 feb 2022
Ability; deduction: certainty and possibility; expectations
You are going to hear two college students called Clare and Fiona. They’re on their way to college when they see someone sitting in a café.
Before you listen, look at the picture.
Do you think the man is with his sister, his girlfriend or his mother?
Listen and check if you were right.
Listen again and answer these questions.
Who does Clare think Danni is with at first?
Fiona doesn’t agree. Why not?
What do the two girls decide to do?
What does Clare want to get?
Why doesn’t Fiona want to?
What does Fiona want to sell?
What is Clare’s opinion of Fiona’s idea?
Listen again and fill in the gaps.
Clare: It might be Danni.
Clare: She ______ his mother.
Fiona: She ______ his mother.
Fiona: He ______ me on my own.
Fiona: She ______ his girlfriend.
Fiona: It ______ him after all.
Look at the sentences above. In which sentences does the speaker:
seem sure that something is true?
think something is possible, but isn’t sure?
We use can or be able to to say that someone has the ability to do something.
We usually use can:
to talk about an ability in a general way:
James can play chess, although he’s only six years old.
Humans can’t see very well in the dark.
to talk about a situation which makes someone able to do something.
The manager can’t see you right now – she’s in a meeting.
You can get tickets to the festival on this website.
this may refer to the future as well as the present:
I can meet you tomorrow because I have a day off.
We use could or was/were able to:
to talk about someone’s ability in the past:
He could / was able to read when he was three but he couldn’t / wasn’t able to catch a ball when he started school.
to talk about a situation which made someone able to do something:
I was able to meet them yesterday because I had a day off.
We do not use could to talk about one situation in the past, but we can use couldn’t:
She was able to (not could) come to the meeting but she couldn’t / wasn’t able to stay for lunch.
They were able to (not could) see the match because they had a day off.
For ability and situations which makes someone able to do something, can is only used in the present tense and could is only used in the past.
Donald Trump can only speak one language (present)
Thomas Jefferson could speak six languages
In all other tenses we use be able to:
We’ll be able to sell the photo to a newspaper. (will future)
They haven’t been able to contact Mary because of the storms. (present perfect)
If you saved enough money, you would be able to visit me in New Zealand. (conditional)
They hope to be able to visit me next year. (infinitive)
We use must when we are sure something is true:
It must be from Steven because he’s in Australia. (= I’m certain it’s from Steven)
To talk about possibility, we can use may, might or could. The meaning is usually the same, but might sounds a little less certain than may or could.
She may be his sister. (= I think there’s a good possibility that she is his sister)
They might have some money. (= I think there’s a slight possibility that they have some money)
We use may, might or could when we think something is possibly true:
The parcel may be / might be / could be from Dad’s friend Tony, because he moved to Australia recently. (= it is possible, not certain, that the parcel is from him)
We use may not / might not (but not could not) when we think something is possibly not true:
It may not be / might not be from someone we know. (= it is possible that it is not)
Notice that could means the same as might and may, but couldn’t is different from might not and may not.
All the verbs in the table can also be followed by be + verb + -ing for a situation which we think is happening now:
Steven might be travelling home at this moment.
He must be looking forward to seeing his friends and family.
must have + past participle when we are sure something
is true:
Steven must have arrived in Perth by now. (= I’m certain he has arrived)
can’t/couldn’t have + past participle when we are sure something is not true:
He can’t/couldn’t have got there yet because it will take at least two weeks. (= I’m certain he hasn’t got there)
might have / may have / could have when we think something is possibly true:
He might/may/could have stopped for a few days on the way. (= it is possible that he stopped)
might not have / may not have when we think something is possibly not true:
He might/may not have had time to do everything he wanted. (= it is possible he didn’t have time)
Notice that could have means the same as might have and may have, but couldn’t have is different from might not have and may not have.
We also use might (not), may (not) and could (but not could not) when we are talking about a possibility in the future:
James may go out to see Steven in Australia next month.
We might get into a lot of trouble, in my opinion.
I think there could be a storm tonight.
Should we get a bigger bag for the potatoes? This one might/may not be strong enough. (not could not be)
When we expect something will happen, we can use should (not) + infinitive without to:
Steven should email us soon. (= I expect he will email)
It shouldn’t be too long before we hear from Steven. (= I expect it will not be too long )
We also use should when we discover that a situation is not as we expected:
This email from Steven says he’s in Melbourne but he should be in Sydney this week. (= I’m surprised because I expected him to be in Sydney)
When we talk about a past situation, we use should (not) have + past participle:
He should have left Alice Springs several days ago. (= I expect he left Alice Springs)
He shouldn’t have had any trouble finding places to stay. (= I expect he didn’t have any trouble)
To talk about the right thing to do in the past we say:
They shouldn’t have talked so much.