In simple words if we notice , use of ‘can’ shows speaker’s physical or mental power.or strength. So  instead of trapping yourselves much in the gust of uncountable rules, try to understand the main concept. Still if you don’t’ want to be left with  any kind of confusion ,the detailed usage of ‘can’ be simply shown in the following ways :-

a. Strength :

     I can open this box.

     You can not touch the height of this roof.

     Can you open the jammed doors of

     this window ?

     You can not run right not. You are looking very frail.

b. Ability:

      I can secure the highest % in my class.

      You can not clear this tough exam.

      So don’t waste your time.

      Can you crack this exam this year ?

c. 100% Possibility / Impossibility: 

          He can run fast but he doesn’t wish

          to participate in the race.

          He can never fail in his mission.

         Can the sun ever set in the east ?

d. Nature:

           She can be an honest girls.

           He can never cheat on me.

           Can’t you have faith on me ?

           You can not be unfaithful to him.

e. Informal Request : 

           Can I use your pen please ?

           Can you give me your notes for

           day ,please?

           Can you pass me that salt ?

f. Permission: 

           Yes, You can use my pen.

           No, You can’t use my pen.

          I can not permit him to go alone.

e.Offer :

           Can I help you to unload the cart ?

           Can I help you completing  your 

           project ?  

           You can take my help if you wish.



Use of Could – Past of Can – shows the speaker’s physical or mental strength that he/she had at a time in the past. Besides, it has some special usage as well that don’t indicate any past activity. So, let’s study step by step and discover how ‘could’ helps to express the mood of the speaker through words. 

 a. Strength:

                      I could run fast when

                      I was a child.

                      You could not write fast

                      when you were in grade 2nd.

                      Could you swim well when

                      you were in school?

                      You could not win that race because

                      you had not practiced well.

 b. Ability:    

                    I could also secure the highest 

                    % in my class if I had not broken my health.

                    You could deal with the coming problem well.

                    Could you play tennis so well at your initial learning stage?

 c.100% Possibility / Impossibility:

                   He could run fast but he wasted all his time looking at others.

                   He could never fail in his mission.

                   could you really not come?

 d. Nature:

                   She could not betray me but she did this time under others’ influence.

                    He could never laugh at me but now he has been changed a lot.

                  Couldn’t you have a bit of faith in me and wait for me?

e. Polite Request:

                  Could I use your pen, please?

                  Could you shift a little, please?

                  Could I also join you for this competition?

 f. Suggestions:

                   Could you help me in raising the fund for the Flood Relief Fund?

                   Could you help me with decorating the bulletin board?

                  After all this time our house has to win. 

 g. The past form of ‘can’ :

                  He told me that he could not attend the party the previous day.

                  He asked me if he could also go with me.

 h. Expected Past Possibility:-

Could is also used when we think about any past condition that is now not in our hand to change. But we expect they could have changed if we had been alert enough. Such kinds of sentences often are found in the fourth kind of Conditional Sentences. 

(Condition Impossible). The structure of which goes like

Past Perfect+,+Future Perfect ( perfect infinitive) 

Thus if we have to show the past possibility of strength, capability, capacity and a prediction that is completely out of our hands, the structure will be like 

Past Perfect+,+ Perfect Infinitive( could have, should have)

The perfect infinitive is made by prefixing the infinitive of the auxiliary verb HAVE to the past participle such as- to have lived, to have taught, could have taught, should have taught, might have stayed.

Eg. If I had filled in the form, I could have also cracked this exam.

       You could also have secured the highest percentage in the 

       class if you had studied well.

        If you had followed my advise, you could also have won this race.



a.Can shows the strength, possibilities, abilities, nature in Present Tense.

       I can Swim fast now.

While ‘ could’  shows the strength possibilities, abilities, nature in Past Tense.       

    I could swim fast when I was a child. 


‘Can’ shows the informal request-

Suppose  you ask your brother-

Can I use your watch, please ?”

You are not very much anxious, he permits you or not and you take it. Because you know 

that he is your brother and he will not mind at all.

‘Could’ shows a polite request:-

But  ‘Could’ is used in a sense of very polite request when you are trapped in such a condition when you feel almost embarrassed to ask help from someone but you have to anyhow. For example – If you go to the bank and forget to take your pen and now you need it urgently so when you ask for a pen from a stranger, obviously you’ll feel embarrassed and shy. So in such condition when you are asking for help, you’ll use ‘ could’.

      ” Could I use your pen, please?”



 At times, we use can for the present. But sometimes we use can when we make present decisions about future ability.


Can you help me with my project? (present)

Sorry, I am leaving for Mumbai today. But I can help you next month. (future)


We often use could for the past. But sometimes we

use could when we make a present polite request as mentioned earlier.

Could I use your mobile, please?

Could I use your colours please ?


1. Akshat____swim fast when he lived in Haridwar.

Correct! Wrong!

2. Just wait . I ____ finish my work within the given time limit.

Correct! Wrong!

3. ______ you please provide me 100 rs change,sir ?I had to leave for the station in a hurry.

Correct! Wrong!

4. ____ you shift a little please, my dear friend ?

Correct! Wrong!

5. I am afraid, I ______ play anymore. I am a lot of tired.

Correct! Wrong!

6. Why didn’t you participate ? You ______ won the race.

Correct! Wrong!

7. I went to every drugstore, but I ______ the medicine.

Correct! Wrong!

8. Oh, great ! You have cooked the complete dinner. ____ I help you to make chapatis ?

Correct! Wrong!

9. If I had listened to my teachers, I ______ led a happy life today.

Correct! Wrong!

10. I ______ solve this problem very easily.

Correct! Wrong!

Published by Buds of Wisdom

I am Meena Kumari, PGT(English)+ B.ed. Teaching is my passion. Love to guide students in Grammar Learning and build up their writing skills.


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