To make my question more understandable, I quoted a student's essay. I have emphasized the instances in bold type. I feel confident enough to tell the difference with some but less so with others. Since my confidence is probably based on my limited knowledge, I have highlighted all of them for the sake of clarity. There are many language errors. I did't correct them because I want to present it the way it is and am afraid that I might misrepresent their ideas. However, if you find it annoying, I would be very pleased to do so. Thanks for your time and efforts.

Factories shouldn't be closed to improve air quality

In recent years, ... More and more factories have been built in China for economic development. Some people hold that we should shut down these factories to improve the country's air. However, I can't agree with them.

On the one hand, shutting down factories would hinder economic growth and leave many people unemployed. This step can only reduce the emission of air pollutants temporarily. [...] These factories are an important part of industrial production. Without them the manufacturing industry cannot continue to function. […] How can they survive in society without jobs? […]

As far as I am concerned, closing factories can not reduce the emission of air pollutants fundamentally …."

  • 2
    That block does nothing to make your question more understandable.
    – AndyT
    Commented Feb 26, 2016 at 13:52
  • You just can, if you know the language well enough.
    – Hot Licks
    Commented Feb 26, 2016 at 13:57
  • 2
    The questions premise is that 'can' (possibility) and 'can' (ability) are two different words with different meanings. Since this is not the case imo (any difference in meaning as far as there is a difference will be made clear by context), the question is based on a false premise. A sentence where 'can' is used to express a possibility might be better served by using might (meaning no. 2) instead.
    – Terah
    Commented Feb 26, 2016 at 13:58
  • 2
    You can edit your question so that we can answer it. Can you show us your research and what you don't understand from it?
    – user24743
    Commented Feb 26, 2016 at 14:14
  • 1
    @Terah But their premise is correct. English speakers use "can" in place of "might" quite often. If the answer is just "you can tell from context" then that's still a valid (if unsatisfying) answer to a valid question.
    – SuperBiasedMan
    Commented Feb 26, 2016 at 14:31

2 Answers 2


You're asking for criteria when can means might and when can means able. The short answer is to try both and accept whichever works. If both give you sensible results, the statement is ambiguous.

Let's take one example with a little context from your original extract and think it through, ignoring the grammatical irregularities:

Besides, these factories are closed, where does those unemployed can go? How can they survive in the society without jobs? So in a word, our country need to take some measures to optimize industrial structure and develop people's awareness to protect environment.

Let's try the first option. If we replace can with might to indicate possibility, we get:

How might they survive in the society without jobs?

This is a question inviting answers. On its own, the question makes sense. However, in context, it seems that the author is posing a rhetorical question, which doesn't invite answers - the intended answer (they can't) is implicit in the question. We therefore reject this option.

Let's now replace can with able to indicate ability. It's not a straight substitution, so we rearrange the sentence a little to get:

How are they able to survive in the society without jobs?

This question can be taken in two ways: as a normal question that invites answers, or as a rhetorical question, not inviting answers. This matches the original. Turning to the context, we find the original to be a rhetorical question, and that's possible with this transformed sentence as well. We consider this admissible.

Since the sentence only makes sense with the can = able interpretation, that's how we interpret it. Likewise for the other instances.

  • Hi @Mari-LouA, I think the system overwrote your edit - it doesn't even appear in the list of revisions. I think my edits survived, so no harm done :) . What did you want to change?
    – Lawrence
    Commented Feb 26, 2016 at 15:40
  • The edit on the OP, I was afraid for a moment that you were citing something I had eliminated. Sorry, I should have been clearer.
    – Mari-Lou A
    Commented Feb 26, 2016 at 15:54
  • @Mari-LouA Ah, I see. My answer relies on context, which is now, um, swiss cheesed. The original block was a little unwieldy, but it wasn't too bad with the keywords in bold. May I suggest to roll back and add a list of the 5 sentences to the question?
    – Lawrence
    Commented Feb 26, 2016 at 16:03
  • @Mari-LouA Scratch that - there's now another answer that relies on the edited version. I'll just add a link to the original in my answer.
    – Lawrence
    Commented Feb 26, 2016 at 16:19
  • Hello @Mari-LouA, I would prefer that you restored the entire essay. This English teacher is clearly doing an outstanding job. Commented Feb 26, 2016 at 16:21

"Can" can be used to mean "able," "permit," "request," "be possible" and "offer." The only way to determine which use is intended is through context and examples. See: http://dictionary.cambridge.org/us/dictionary/english/can

In the five examples that survived your edited question,

I can't agree with them; This step can only reduce the emission of air pollutants temporarily; and, Without them the manufacturing industry cannot continue to function;

appear to mean "able," while

How can they survive in society without jobs? and, Closing factories cannot reduce the emission of air pollutants fundamentally;

appear to mean "be possible." Is this your understanding as well?

Please read the other examples at the Cambridge Dictionary link provided above for more information.

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