In this post, we will talk about the use of “can” and “be able to”. “Can” and “be able to” are often interchangeable, but there are some occasions where only one of them is correct.
Both “can” and “be able to” is used:
1. In the present tense to talk about an ability to do things. In this case, “can” is more common, while “be able to” sounds more formal and less natural.
- “I can play guitar.” ✔
- “I am able to play guitar.” ✔
- To talk about the ability to do something on a specific occasion in the future.
- “I can do the interview tomorrow.” ✔
- “I am able to do the interview tomorrow.” ✔
- “When I’m done writing this essay, we can hang out.” ✔
- “When I’m done writing this essay, we will be able to hang out.” ✔
3. To talk about an ability that someone doesn’t have anymore.
- “I could stay up until 3 AM when I was a student.” ✔
- “I was able to stay up until 3 AM when I was a student.”✔
We only use “can” or “could” in the present tense to talk about possibilities.
- “With that much preparation, I think they can win the academic bowl.” ✔
- “With that much preparation, I think they are able to win the academic bowl.” ✖
We only use “was/were able to” to talk about something we succeeded in doing on a specific time in the past.
- “I was able to sleep last night.” ✔
- “I could sleep last night.” ✖
However, it is okay to use either “could not” or “was/were not able to” in negative statements about something the past.
- “I couldn’t ride a bike when I was a teenager.” ✔
- “I wasn’t able to ride a bike when I was a teenager.”✔
- “We couldn’t get tickets to the premiere yesterday.” ✔
- “We weren’t able to get tickets to the premiere yesterday.” ✔
By the way, you can read more about the usage of “can” vs. “could” as well as other modal auxiliary verbs in this article. Feel free to drop a comment if you have any question.
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