*Modals – Can/Could (Possibility)

A Modal verb is a type of auxiliary (helping) verb that has no meaning on their own but it modifies the main verb, changes his meaning and gives more details about action.

Can and Could are types of auxiliary modal verbs used to express the idea of ability or permission. Could is the past tense of Can and the conditional form. Therefore Could is used to express ability in the past and it is also used in polite expressions asking permission when used as a conditional form.

Can/Could is used as Modal Verb and here are the three forms:

Affirmative

The Affirmative form of the verb Can/Could has this structure:
Subject + can/could+ verb.

PERSON CAN/COULD VERB
I can/could read
You can/could read
He can/could read
She can/could read
It can/could read
We can/could read
You can/could read
They can/could read

Negative

The Negative form of the verb Can/Could has this structure:
Subject + can/could+ not + verb.

PERSON CAN/COULD NEGATION VERB SHORT FORM
I can/could not read can’t
You can/could not read can’t
He can/could not read can’t
She can/could not read can’t
It can/could not read can’t
We can/could not read can’t
You can/could not read can’t
They can/could not read can’t

*Short form of the Negative form is: “can’t

Interrogative

The Interrogative form of the verb Can/Could has this structure:
Can/could + subject + verb + (?).

CAN/COULD PERSON VERB Q.M.
Can/Could I read ?
Can/Could you read ?
Can/Could he read ?
Can/Could she read ?
Can/Could it read ?
Can/Could we read ?
Can/Could you read ?
Can/Could they read ?

*The form is always the same, even for the third person.

Present and Past:

  • I can swim. (I am able to swim)
    I could swim when I was a boy.  (I was able to swim when I was a boy)

Conditional (Polite Expressions):

  • Can you open the window?
    Could you open the window? (more polite)

We use Can/Could to express ability or permission.

Can expresses ability or permission in the present and Could in the past.

Could is also a conditional of Can and is used in polite expressions asking permission and ability.

We use modal verbs Can and Could to express ability and permission. They have all three forms of Affirmative, Negative and Interrogative. The structure is as follows:

  • AffirmativeSubject + can/could+ verb (e.g. I can run fast./I could ran fast when I was little.);
  • NegativeSubject + can/could+ not + verb (e.g. I cannot run fast./I couldn’t run fast when I was little.);
  • InterrogativeCan/could + subject + verb + (?) (e.g. Can you run fast?/Could you run fast when you were little?).

*The form is always the same, even for the third person.

Could is also the conditional form of Can. It can be used in conditional mode and in polite expressions.

For example:
— “I could  give you a ride, but I’m going the other way.” = Conditional mode.
— “Could you open the window?” = Polite expression.

Let’s revise this content within the [Form] section. Take a look at the [Example] section that shows its use within a context.