🔑 Key Difference

• Could is commonly used to express ability in the past or to make polite requests.
• Able to focuses on the actual capability to do something, often in more specific situations or when showing that someone succeeded in doing something.

1. Using “Could”

Could is a modal verb, and it’s used in various situations:

a. Ability in the Past

We use could to talk about abilities someone had at an earlier time, but only when referring to general abilities, not specific moments.

• Example:
  “When I was a child, I could swim really fast.”
  (General ability in the past)

However, if you’re talking about a specific moment in the past where someone succeeded in doing something, could is usually not used. Instead, you would use was/were able to (see more on that below).

b. Polite Requests

Could is often used to ask someone to do something in a polite way.

• Example:
  “Could you pass me the salt?”
  (Polite request)

2. Using “Able to”

Able to is a phrase we use when referring to someone’s actual capability or when they manage to do something, often emphasizing success in a particular situation.

a. Specific Situations in the Past

Unlike could, able to is used to describe specific moments in the past when someone successfully did something, especially when it wasn’t easy.

• Example:
  “Although it was raining, she was able to finish the race.”
  (She succeeded in doing it, despite the difficulty.)

b. Present and Future Capability

You can also use able to to talk about someone’s ability in the present or future.

• Example:
  “I’m able to meet you tomorrow.”
  (Talking about capability in the future.)

📝 Practice Time!

Fill in the blanks with could or able to:

1. When I was younger, I ________ run 10 miles without getting tired.
2. She wasn’t ________ to come to the meeting yesterday because she was sick.
3. ________ you help me with my homework, please?
4. We were finally ________ to find the lost keys after searching for hours.

✅ Answers:

1. When I was younger, I could run 10 miles without getting tired.
2. She wasn’t able to come to the meeting yesterday because she was sick.
3. Could you help me with my homework, please?
4. We were finally able to find the lost keys after searching for hours.

💡 Pro Tip:

• Use could for general abilities in the past and polite requests.
• Use able to when you want to show that someone succeeded at something, especially in a specific situation.