Expressing Ability: Can, Could, and Be Able To

1. Present Ability: Can & Am/Is/Are Able To#

To express ability in the present or general ability, we use can or am/is/are able to.

A. Can (Most Common)

• Structure: Subject + can + Verb 1
• Use: Used for general abilities or skills that a person has right now.
• Example: I can speak three languages fluently.
• Example: She can run very fast.

B. Am / Is / Are Able To (More Formal)

• Structure: Subject + am/is/are + able to + Verb 1
• Use: Used in the same way as can, but sounds more formal.
• Example: We are able to complete the project on time.
• Example: The doctor is able to see you now.

2. Past Ability: Could & Was/Were Able To#

To express ability in the past, we use could or was/were able to. There is an important difference in usage between them.

A. Could (General Past Ability)

• Structure: Subject + could + Verb 1
• Use: Used to describe general abilities or talents we possessed in the past.
• Example: When I was a child, I could swim across the lake.
• Example: She could play the violin beautifully when she was younger.

B. Was / Were Able To (Specific Past Success)

• Structure: Subject + was/were + able to + Verb 1
• Use: Used when describing a specific, single occasion in the past where we succeeded in doing something, often despite difficulty.
• Correct: The door was locked, but we were able to open it. (Specific occasion).
• Incorrect: The door was locked, but we could open it.

3. Future Ability: Will Be Able To#

Since can has no future form, we must use will be able to to express future ability.

• Structure: Subject + will + be able to + Verb 1
• Example: After you finish this course, you will be able to speak English with confidence.
• Example: They will be able to join us for dinner tomorrow.

Next, we will look at Permission and learn how to ask for, give, and deny permission using modal verbs.