1). His dance was unbelievable! I don't know if I can do do it.

2). His dance was unbelievable! I don't know if I could do it.

What is the difference in meaning between these two sentences?

2 Answers 2


The first one is to be used if the speaker is actually going to try to do it.

The second is to be used in the hypothetical situation, that is, if the speaker has no intention of trying to do it.

  • Got it. But is there any possibility for the second sentence to represent past ability? Jun 29, 2020 at 15:49
  • 3
    No, then that would be "I don't know if I could have done it." Jun 29, 2020 at 20:13

Can and could can be used in different situations, such as possibility, ability, permission, requests, offers, and suggestions. The can and could here are used to express ability here, so I'll just focus on it here, if you have any doubts about the other usages, you can tell me in the comments.

Using can/could to talk about ability

The difference between can/can't and could/couldn't is the tense.

We use can and can't to talk about the ability to do something at a specific time in the present or future:

I can see you.
Help! I can't breathe!

We use could and couldn't to talk about the past:

She could speak several languages, but she forget most of them now.
They couldn't dance very well.

However, if you take a closer look, this is not the situation in the example:

His dance was unbelievable! I don't know if I can/could do it.

The difference here is that could can be used to say that someone had the ability or opportunity to do something, but did not do it:

She could learn Swahili, but she didn't want to.
I could dance all night.

Consequently, the first one is used if the speaker wants to really try the unbelievable dance.

The second one is used when the speaker doesn't intend to try doing it.



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