Difference between can and able

Anonymous wrote:

is this sentence correct "I cant able to read"

Hi Anon,

The difference is subtle. [Can] can be used interchangeably with [to be able to] in certain tone and construction of sentences and context but not always. Can- is a safer and more common word to use without tangling up in meanings. We can say “He was able to finish the job in 1 hour” which is fine and it meant the job was completed. But “he could finish the job in 1 hour” offerred the meaning that the the job was still not completed.  

“She can be a dangerous woman” – means that she is capable of carrying out acts of harm. But “able” is not an option here.

We can say “he can be quite temperamental at times” but we can not say “he is able to be temperamental ….”.

Despite of many failures in his early adulthood, he was able to pull himself back up. This meant he made something of himself.

Could – you can’t use it in this context.

He can consume a large quantity of food if you let him = he is able to consume a large amount of food….  Yes, in this contest, they bear practically the same meaning.

The ability to identify when and where to use which one can not be explained in a couple of quick lessons. It requires learners’ nonstop efforts to read, observe and practice in order to improve. Everyone is able to / can improve his English if he put in enough effort.

Goodman wrote:

We can say “He was able to finish the job in 1 hour” which is fine and it meant the job was completed. But “he could finish the job in 1 hour” offerred the meaning that the the job was still not completed.

Mmmhhh, not sure about that.

1. "He could have finished the job in 1 hour" means he didn't complete it (at least, not in one hour).

2. "He could finish the job in 1 hour" refers to a possibility in the present (could works as may/might /can to express uncertainty) or to a general ability in the past (something like "he was such a good employee that he used to finish the job in 1 hour", compare "I could play the piano" -- now I cannot anymore!).

3. "He was able to finish the job in 1 hour" refers to ability in the past in a specific circumstance (emphasising effort and achievement: maybe the other employees spent much longer in doing the same job).

Am I wrong? Particularly, I can't understant why you think that with could the action is not complete.

Um…Let me see how this can be explained without sinking deeper into mud…

Let’s say “Mary was able to make the date with Mike last night because she finished her work in time”. – The date took place and she went out with Mike.

Mary could have called Mike that she might not be able to make the date because she may not be able to finish her work in time.

I hope by using the combination of “be able” and “can” I could show you the contrast.

When we say something “could have” it has a tone that  it didn’t happen, as in the example I gave.

If  I said “I could have taken the train (but I didn’t because I have to get up too early)”, it hints I prefer to drive, so taking the train never happen.

And I agree with Selector.  He wrote: I would like to add that "to be able to" can be tricky.

Use "can" if you're not so good at grammar.
"to be able to" is generally used talking about specific achievements, but "can" is used talking about general abilities

 You can't use "to be able to" talking about something that is happening while you are speaking.

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Back to the I hour job question...  If he completed the job in 1 hour, he is finished with it.  So “could” should not be used in the context at all, in my opinion. Because to me, "could" has an implied tone of “otherwise”.  i.e. I could work for IBM( but I chose Cisco).

 For future context, I can say “ I can get it done in 30 minutes” is the same  as “ I believe I am able to get it done in 30 minutes”.  I don’t think I can explain to complete satisfaction the intricate use between [can], [could] and [ be able to]. Perhaps other experts can help comments on it.

CalifJim wrote:

Post:132706

Everything I wanted to say but "was unable to" come up with it!