Using Can, Could & Be Able To -- Explained in Urdu
can for possibility and ability
We use can to talk about what is possible, what we are able or free to do:
She can drive a car.
John can speak Spanish.
I cannot hear you. (I can't hear you.)
Can you hear me?
Normally, we use can for the present. But it is possible to use can when we make present decisions about future ability.
Can you help me with my homework? (present)
Sorry. I'm busy today. But I can help you tomorrow. (future)
can for requests and orders
We often use can in a question to ask somebody to do something. This is not a real question - we do not really want to know if the person is able to do something, we want them to do it! The use of can in this way is informal (mainly between friends and family):
Can you make a cup of coffee, please.
Can you put the TV on.
Can you come here a minute.
Can you be quiet!
can for permission
We sometimes use can to ask or give permission for something:
Can I smoke in this room?
could for past possibility or ability
We use could to talk about what was possible in the past, what we were able or free to do:
I could swim when I was 5 years old.
My grandmother could speak seven languages.
When we arrived home, we could not open the door. (...couldn't open the door.)
Could you understand what he was saying?
be able to for ability
We use be able to to express ability. "Able" is an adjective meaning: having the power, skill or means to do something. If we say "I am able to swim", it is like saying "I can swim". We sometimes use be able to instead of "can" or "could" for ability. Be able to is possible in all tenses - but "can" is possible only in the present and "could" is possible only in the past for ability. In addition, "can" and "could" have no infinitive form. So we use be able to when we want to use other tenses or the infinitive. Look at these examples:
I have been able to swim since I was five. (present perfect)
You will be able to speak perfect English very soon. (future simple)
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