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Expressing Ability… Usage of Can and Could

We come across many situations in life where we need to express our ability/possibility to do something. Our expression should be clear or we may convey a wrong message in such situations. We learn in this module how to express our ability and expressions related to our past ability that was used and some times couldn’t be used.

Read the following
Example 1:
Siddu: Can you do the sum that was given
by the teacher yesterday?

Dheeraj: Yes, I can. The logic is very simple.
Siddu: Can you lift this big table?
Dheeraj: No, I can’t. I could do it when I was young.
Siddu: Shall we go to shopping in the afternoon?
Dheeraj: I can come with you only after 4pm.

Example 2:
Siddu: Why do you look so sad?
Nishi: I missed my first rank in just two marks.
Siddu: If you had prepared solving the problems along with theory questions, you could have got those two marks.
Nishi: Yah! I could do those problems, but I did not remember the sequence while solving it. Thank you for the suggestion.

Example 3:
Abhi: Hai Sid!
Siddu: Hello! Abhi, How are you?
Abhi: Fine, Thanks. I could n’t hear from you since a month.
Siddu: Yah! I’m sorry! I didn’t tell you that I got a Job in HSBC. Presently I’m deputed to Hyderabad branch. But I do not know any one there.

Abhi: You can speak to Nishi. He is also in Hyderabad.
Siddu: Oh! That’s a great idea. Could you please give me his mobile number?
Abhi: Sure.
Siddu: Thank you. See you later.

Simple sentences are constructed using ‘be’ forms of the verbs. We know that verbs are the words that give life to the sentence, in other words verbs complete the meaning of an expression. They may state about the existence of a subject, or say about an action in the sentence.
  • He is a student. ( being or existence)
  • He writes a poem ( action)
These verbs have different forms and functions.
‘Be’ forms, ‘do’ forms, perfect tense verbs, Modal verbs and main verbs or action verbs. Modal verbs are verbs used for specific purpose. They convey a particular meaning in particular situations.

In this module we learn the use of ‘can’, and ‘could’
  1. It is mostly used to express ‘ability’ and ‘possibility’
    • We can see the beach from our terrace.
  2. Can is an alternative to ‘able to’ but not always. Observe the difference
    • I can use the computer. (Certain)
    • She is able to use computer after one month training. (Uncertain)
  3. Can is sometimes used in the sense of ‘may’ to give permission.
    You can come to my house at any time to use the computer.
  4. When can is used in questions it might be asking about – ability, permission and possibility.
  5. But, ‘could’ is used in questions to request, and to ask permission apart from asking past ability?
    Can you come with me?
    Can Ram speak English?
    Can I take your book today?
    Could you do this favour for me?

  1. It is mostly used to express ‘ability’ and ‘possibility’ in the past
    • I could walk for a mile without getting strained. (past ability, but not now)
    • We had lunch at Taj, I could eat few items. (Past ability)
  2. It is used to talk about general permission in the past
    • When we were given the permission we could use those laboratories.
  3. On certain occasions we can use only ‘able to’ expresses different meaning than ‘could’ could.
    • When the car behind dashed my bike, I was able to escape.
    • When the car behind dashed my bike, I could escape.
  4. Could expresses future possibility
    Siddu: Where shall I go this evening?
    Dad: We could go to City Central
  5. Could is used for unrealistic things.
    Observe the use of can and could
    • I can solve all these mathematical problems (certain)
    • I think I could solve all these problems ( not certain)
  6. Could is used for polite requests
    Could you please help me in getting the things ready?
    Could you lend me the text book for two days?
Could have
  1. 'Could have' is used to talk about something somebody was capable of doing but didn't do.
    Ram could have won at least a bronze medal, but he did not practice well.
    I could have helped him if he had asked me.
  2. Could have is used to speculate about what has happened.
    They could have come early to book the tickets.
In brief…
Asking for permission
Asking for
ability alternative to ‘able to’
Ability in the past
Possibility in the past
Polite request
Unrealistic expression
future possibility
Could have Speculation about past
Ability / possibility in the past
but did not take place.

Now go back to the previous conversations and observe the use of ‘can’ and ‘could’ in different situations. Try to link the usage with the few rules given. This helps you to understand better.
Published date : 29 Sep 2010 06:37PM

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