Let’s find out!
1. Can → to talk about abilities in the present or the future.
He can speak English fluently.
Can you come with us on Saturday?
2. Could → to talk about general abilities in the past.
I could jump much higher when I was younger.
She could play the piano when she was a child.
“When I was younger” and “when she was a child” are general
abilities about a long period in the past.
However, there are many situations where we can’t use “can” or “could”
to talk about abilities, because in some cases, there is no form of “can”
or “could” we can use. So sometimes we need to use non-modal verbs.
The one we learn today is “be able to“.
“Be able to” vs “can”
1. Same meaning as “can”
He can speak English fluently.
= He is able to speak English fluently.
2. Present perfect form (we can’t use “can”)
I have been able to swim since he was two years old.
3. Verb with -ing (we can’t use “can”)
I like being able to choose my own working hours.
“Be able to” vs “could”
1. A specific ability at a specific moment in the past
In positive sentences, we can’t use “could”.
It was hard work, but we were able to finish everything on time.
“It was hard work” → a specific moment
“Everything” → something specific
“Finish everything” → a specific ability
In negative sentences, “couldn’t” = “be not able to”
It was hard work, and we couldn’t finish everything on time.
= It was hard work, and we were not able to finish everything on time.
2.The two meanings of “could”
the past meaning (= was/were able to)
I couldn’t help you because I had too much to do.
= I wasn’t able to help you because I had too much to do.
The hypothetical meaning (= would be able to)
I couldn’t help you even if I wanted to.
= I wouldn’t be able to help you even if I wanted to.
Conclusion:
1. We can use “can” to talk about abilities in the present or future, and
use “could” to talk about general abilities in the past.
2. “Can/could” and “be able to” generally have the same meaning, but
in some cases we need to use “be able to”, for example:
In positive past sentences which talk about a specific ability.
We need to use a verb with -ing.
Some tenses where “can/could” don’t exist such as the present perfect
tense (have/has + done)
3. “Could” can have two meanings: past or hypothetical.
4. “Be able to” can be used in every case.
Practice:
Replace “could” in the sentences with the suitable forms of “be able to”.
1. We could work together if you wanted. Would be able to
2. I couldn’t do it last week because I was badly ill.
Be = is/am/are/was/were
'can' and 'could'
Level: beginner
Possibility and impossibility
We use could to show that something is possible, but not certain:
They could come by car. (= Maybe they will come by car.)
They could be at home. (= Maybe they are at home.)
We use can to make general statements about what is possible:
It can be very cold here in winter. (= It is sometimes very cold here in winter.)
You can easily get lost in this town. (= People often get lost in this town.)
We use can't or cannot to say that something is impossible:
That can't be true.
You cannot be serious.
Level: intermediate
We use could have to make guesses about the past:
It's ten o'clock. They could have arrived by now.
Where are they? They could have got lost.
We use could to make general statements about the past:
It could be very cold there in winter. (= It was sometimes very cold there in winter.)
You could easily get lost in that town. (= People often got lost in that town.)
We use can't have or couldn't have to say that a past event was impossible:
They know the way here. They can't have got lost!
If Jones was at work until six, he couldn't have done the murder.
Ability
Level: beginner
We use can and can't to talk about someone's skill or general abilities:
She can speak several languages.
He can swim like a fish.
They can't dance very well.
We use can and can't to talk about the ability to do something at a specific time in the
present or future:
I can see you.
Help! I can't breathe.
We use could and couldn't to talk about the past:
She could speak several languages.
They couldn't dance very well.
Level: intermediate
We use could have to say that someone had the ability or opportunity to do something, but did
not do it:
She could have learned Swahili, but she didn't want to.
I could have danced all night. [but I didn't]
Permission
Level: beginner
We use can to ask for permission to do something:
Can I ask a question, please?
Can we go home now?
could is more formal and polite than can:
Could I ask a question please?
Could we go home now?
We use can to give permission:
You can go home now.
You can borrow my pen if you like.
We use can to say that someone has permission to do something:
We can go out whenever we want.
Students can travel for free.
We use can't to refuse permission or say that someone does not have permission:
You can't go home yet.
Students can't travel for free.
Requests
We use could you … as a polite way of telling or asking someone to do something:
Could you take a message, please?
Could I have my bill, please?
can is less polite:
Can you take a message, please?
Offers
We use can I … to make offers:
Can I help you?
Can I do that for you?
We sometimes say I can ... or I could ... to make an offer:
I can do that for you if you like.
I could give you a lift to the station.
Suggestions
We use could to make suggestions:
We could meet at the weekend.
You could eat out tonight.
Questions and negatives
We make questions by putting the subject after can/could:
Can I ...? Can you ...?
Could I ...? Could you ...?
etc.
The negative form is can't in spoken English and cannot in written English.
We sometimes say cannot, but it is very emphatic.
The negative form of could is couldn't in spoken English and could not in written English.
Now that we’ve refreshed the basics, see if you can complete the following sentences
correctly.
1. _could__ you hear the fireworks from your house last night?
Can
Can't
Could
2. Do you think you __will be able to_ write that report by Tuesday? I know you’re very
busy.
will be able to
have been able to
couldn't
3. I __can_ touch my toes. See!
can
could
will be able to
4. I __couldn't_ spend another moment in that restaurant. It was too noisy.
couldn't
have been able to
can't
5. I __can_ never seem to get the temperature right.
can
can't
to be able to
6. _to be able to__ play professional tennis, you must be extremely fit.
To be able to
Couldn’t
Will you be able to
7. _can__ you play an instrument?
Able to
Can
Couldn't
8. I'm afraid I _won't be able to__ attend the meeting, I’m on business in Japan.
won’t be able to
can
will be able to
9. _couldn't__ you have brought it to me at work?
Couldn't
Cannot
Will be able to
10. They _were able to__ save the men from the sinking ship.
was able to
could to
were able to
a. the only one of its kind
1. A marathon is g b. a piece of cloth supported by poles and rope that is
used for sleeping outside
2. A course is i
c. a specific amount of something that you are
3. The format of something is j
allowed to have
4. A stage is d
d. a step in a longer process
5. Terrain is e
e. a type of land
6. Something that is unique is a
f. to become interested in
7. A tent is b
g. a 26-mile race
8. A ration is c
h. something that happens to you that affects the way
9. To get into something is f you think or feel
10. An experience is h i. the path of a race
j. the way its parts are arranged
