Modal Verbs: Can or Could?


MODAL VERBS —– CAN” OR “COULD

Can and Could are two of the most used modal verbs in English. These are auxiliary verbs ( modal auxiliary verb ). 



General Structures of  “Can” and “Could” in a Sentence

POSITIVE FORM (+) :  Subject + CAN/COULD + Verb (  first form of the verb )

NEGATIVE FORM (-) : Subject + CAN/COULD + NOT + Verb (  first form of the verb )

QUESTION FORM (?) : CAN/COULD+ Subject + Verb (  first form of the verb )

Contraction for ” CAN NOT and COULD NOT “

  • can not       –>    can’t   
  • could not   –>    couldn’t





Using ” CAN ” and ” COULD

1.

Can is used to express that someone is able to do something. ( Present Ability )

Examples:

  • I can speak four languages.
  • She can drive a car.

Could is used to express that someone is able to do something in the past. ( Past Ability )

Examples:

  • He could play football well when he was a kid.
  • We could not ( couldn’t ) get a job at those times.

2.

Can is used to express that something is possible.  (  Present Possibility )

Examples:

  • Alcohol can cause canser.
  • They can stay with us when they come.

Could is used to express that something is possible in the past.  (  Past Possibility )

Examples:

  • A lot of crime could be prevented.
  • This new method could be an important step in success.

3.

Can is used to ask or give permission for something. ( Informal Permission )

Examples:

  • Can I use your book, please? ( ask for permission )
  • If you want, you can go to the park. ( give permission )

Could is also used to ask or give permission for something. “COULD” is used as a more formal and polite form of “CAN”. ( Polite Permission )

Examples:

  • Could I take your book, please? 
  • Could I please use your computer?

4.

Can is used in a question, which is not a real question, to ask somebody to do something. We want somebody to do our request ( in an informal way, especially between friends or family ). ( Informal Request )

Examples:

  • Can you make me coffee?
  • Can you hand me the pen?

Could is used in a question, which is not a real question, to ask somebody to do something in a polite way. “COULD” is used as a more formal and polite form of “CAN”. ( Polite Request )

Examples:

  • Could you lend me this book?
  • Could you tell me where the post office is, please?

5. 

Can is used in offers to help someone or to do something for someone. ( Informal Offer )

Examples:

  • Can I help you?
  • If they like, I can carry some bags for you.

Could is used for making a suggestion. ( Suggestion )

Examples:

  • If you want,we could go out for dinner after school?
  • You could always call me every day of the week if it is necessary.

6.

For ” CAN NOT “;

It is used in negative saying ( when we are sure that something is not true or something is surprising )

Example:

  • It can’t be raining. The sun is shining and there are no rain clouds.

( The speaker means that s/he is sure that it isn’t raining because the sun is shining and there are no rain clouds.)

It is also used in negative saying ( when something is forbidden or not allowed )

Example:

  • You can’t park the car there.

For ” COULD NOT “;

It is used in negative saying ( when something is impossible to happen or untrue)

Example:

  • He couldn’t have this house. He is poor.

( The speaker means that it’s not or it might not be possible because the sun is shining and there are no rain clouds.)

7.

For ” COULD ” AS A CONDITIONAL FORM OF “CAN”;

When we are talking about past time in conditionals, we use “could” instead of “can”.

Examples:

  • If you called me, I could find you some suggestion.
  • could visit many places if I had more money.

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