Grammar notes: ability Can and could

Grammar notes: ability
Can and could
Can and could are modal verbs. They are sometimes called modal auxiliaries because they are generally used with
another verb and help us to understand that verb.
Examples of this auxiliary use are:
I can swim ability
Can I smoke? permission
Could you lend me £5? asking for something
In this section I'll only be looking at the 'ability' aspect of can and could.
General characteristics of can and could
They do not add -s in the 3rd person singular:
I can swim.
He can swim.
They could all drive before I could.
He could drive before I even had a bike.
To make a question you don't have to use an auxiliary verb, justinvert the subject and the modal verb:
Can you swim?
Can he swim?
Could she read when she was three?
To make a negative sentence, add not or n't to the modal verb:
I can't swim (or I cannot swim. Cannot is one word)
Can't you swim?
We couldn't finish the exam in time.
Be able to
As I said above, can and could are modal verbs, and modal verbs don't follow the normal rules for verbs. For example,
they don't have an infinitive or an -ing form.
For this reason can and could are impossible to use when you need to use the infinitive, the gerund or a continuous
tense (though the continuous form would be impossible anyway!).
Being modal verbs also means they don't necessarily have a form that can be used for the past or the future, though
in very general terms can is used to refer to the present and could is used to refer to the past.
When you can't use can or could, you need to use a form of be able to. This means exactly the same as can and could.
Some examples:
I'm sorry, but I won't be able to come tomorrow.
Being able to speak another language is very useful.
You should be able to do this. It's easy!
Tense chart
To make things clearer, have a look below. It shows when you can use can, could and be able to.
Remember that be able to can always be used, but that English speakers use can and could whenever they can. Be
able to sounds more formal and not English.

present simple can or am/are/is able to
present continuous ------ ------
past simple could or was/were able to
past continuous ------ ------
present perfect ------ has/have been able to
past perfect ------ had been able to
future ------ will be able to
infinitive ------ (to) be able to
gerund ------ being able to
conditional could or would be able to

Notes about tenses
The chart above is only intended as a rough guide. As always with English verbs, a lot of the time the tense you use
depends on what you're talking about.
For example, can can be used to refer to timetables or schedules in the future, just as the present simple is used
normally: I can't come tomorrow, but I can come at 3 o'clock next Thursday.
When talking about the past there's a difference between could and was/were able to: could is used in a more general
sense while was/were able to is used to talk about more specific occasions: I could run really fast when I was younger.
But then I started smoking and my sister was able to beat me every time we had a race.
However, when you talk about the past in the negative couldn't and wasn't/weren't able to are completely
interchangeable:
Sorry, I couldn't come yesterday.
Sorry, I wasn't able to come yesterday.
The conditional forms are also interchangeable:
I could go on holiday if I had more money.
I'd be able to go on holiday if I had more money.


Ability

Choose the correct option to complete the sentence. There may be more than one possibility - decide which sounds
best.

1 __________ speak a foreign language is always useful when you go abroad.

a Be able to b Being able to c Can d I can

2 I __________ touch my toes since I started drinking beer.

a can't b am not able to c couldn't d haven't been able to

3 You must __________ swim if you want to come on the boating holiday with us.

a can b be able to c to be able to d will be able to

4 There was a fire in his office but he __________ escape through a window.

a can b could c could to d was able to

5 My grandfather was an excellent athlete. He __________ run a mile in just over four minutes.

a can b could c couldn't d was able to

6 The doctor says he will never __________ play tennis again after his accident.

a can b could c be able to d to be able to

7 After his car crashed he was so confused that he __________ tell the police who he was or where he was going.

a could b couldn't c didn't could d wasn't able to

8 I live alone because I like __________ come and go as I please.

a I can b to can c being able d to be able to

9 I had saved up enough money so I __________ gone on holiday, but I decided to paint my flat instead.

a can have b was able to c could have d was able to have

10 The police ran after the burglar, but she __________ get away from them.

a was able to b could c has been able to d was being able to

Ability
Fill in each blank using can, could or be able to in the correct form or tense.


1 ________ speak a foreign language is very useful when you go abroad.

2 I ___________ touch my toes since I started drinking beer.


3 You must ___________ swim if you want to come on the boating holiday with us.

4 There was a fire in the office but he _______ escape through a window.


5 My grandfather was an excellent athlete; he ________ run a mile in just over four minutes.


6 The doctor says he _____ play tennis again after his accident.


7 After his car had crashed, he was so confused that he _____ tell the police who he was or where he was going.


8 I like living alone because I like ______ come and go as I please.


9 I had saved up enough money so I ______ gone on holiday, but I decided to paint my flat instead.


10 The police ran after the burglar, but she _____ get away from them.


11 I _____ speak Spanish now that I have been living here for years, but I ___ speak a word when I arrived.



12 I've been ringing him all day, but I ______ get through yet.