In English we use can to talk about our ability to do something:
I can drive = I know how to drive
Grammar rules
“Can” is a modal verb. This means you don’t have ‘s’ on the end of “can” for he / she. “Can” is the same for all subjects.
It’s followed by the infinitive of the verb without “to”:
I can drive.
You can drive.
He can drive.
She can drive.
We can drive.
They can drive.
The negative is cannot or can’t:
I cannot / can’t drive.
You can’t drive.
He can’t drive.
etc
To form a question, invert the subject and “can”:
Can you drive?
Can he drive?
etc
Short response
Yes I can / No I can’t
Yes he can / No he can’t
Example:
Can she drive?
Yes she can / No she can’t.
Pronunciation tip!
“Can” rhymes with “ran” in question forms and short answers.
“Can you swim?”
“Yes, I can.”
In affirmative sentences it becomes /kun/: the “a” sound becomes a short schwa “uh” sound.
For example, “I can swim” = “I /kun/ swim”
“Can’t” rhymes with “aunt” (as in “car – nt”).
In the past
We use could to talk about our ability in the past:
“I could run fast when I was a child.”
The negative is couldn’t:
“I couldn’t speak a foreign language when I was a child.”
“Could” and “couldn’t” are also modals, which mean they don’t add ‘s’ for the third person, and an infinitive without “to” follows them. You form negatives and questions in the same way as “can”.
Be able to
You can use “be able to” in the present simple tense. It’s more formal than “can”. Remember to change the “be” to the correct verb ending for the subject:
I am (am not) able to attend the meeting.
You are (aren’t) able to leave the country without a passport.
He is (isn’t) able to drive a car.
She is (isn’t) able to read without glasses.
We are (aren’t) able to buy a new house.
They are (aren’t) able to walk very far.
In the past, change am, are, is to was or were:
I was / wasn’t able to come to your party.
We were / weren’t able to leave on time.
“Be able to” is also useful in situations when you can’t use “can” or “could”. In English grammar, you can’t have two modals together. For example, if you want to talk about ability in the future, you can’t use “will can”, but you can use “will be able to“, because “be able to” is not a modal.
I will be able to attend the meeting tomorrow.
You will be able to enter the competition.
He will be able to get the next flight.
She will be able to help you.
We will be able to attend the wedding.
They will be able to pass the exam.
In the negative form, use “won’t” (or “will not“):
I won’t be able to attend the meeting.
She will not be able to leave the office before 5pm.
To make the question form, invert “will” and the subject:
Will you be able to come to the party?
Will he be able to lift that box?