Usage of "Can," "Could," and "Be Able To" in English

Modal verbs play an important role in English grammar by expressing ability, possibility, and permission. Three of the most commonly used structures in this category are "can," "could," and "be able to." Understanding their differences helps you use more accurate expressions in both spoken and written communication.

Usage of "Can" "Can" is used to express present or general ability. It is also used to indicate possibility or permission.

Positive Example:

• "She can swim very well."

  In this sentence, "can" indicates that the person has the ability to swim.

Negative Example:

• "I can't play the guitar."

  Here, "can't" expresses that the person does not have the ability to play the guitar.

Usage of "Could" "Could" is the past form of "can." However, it is also used to make polite requests or describe hypothetical situations.

Positive Example:

• "When I was a child, I could run for hours."

  Here, "could" is used to describe an ability the speaker had in the past.

Negative Example:

• "She couldn't understand the question."

  In this sentence, "couldn't" is used to indicate that the person was unable to do something in the past.

Usage of "Be Able To" Unlike "can" and "could," "be able to" can be used with all tenses. It is especially preferred when referring to successfully completed actions in the past or when "can" cannot be used grammatically.

Positive Example:

• "Despite the heavy traffic, I was able to arrive on time."

  In this sentence, "was able to" is used to emphasize a successfully completed action in the past.

Negative Example:

• "He wasn't able to fix the car."

  Here, "wasn't able to" indicates that the person was not successful in a particular situation.

Key Differences Between "Can," "Could," and "Be Able To"

• "Can" is used for present or general abilities.

• "Could" is used for past abilities, polite requests, or hypothetical situations.

• "Be able to" can be used in all tenses and is particularly preferred when emphasizing a specific achievement.

Using these modal verbs correctly will improve your fluency in English and make your expressions clearer and more effective.