I have an English exercise which says:

It is very cloudy, I think it ______ rain.


  • might
  • must
  • can
  • can't

I don't know which option is correct and I want a short explanation. I think 'can' is the correct option, but it can be 'might' too, I don't think that 'must' is the correct one at all.


2 Answers 2


Every sentences has a difference meaning expect must.

Here are the rules:

It can rain

This expresses what the speaker believes is a general truth or known fact, or a strong possibility.

It could/may rain

This does not express a general truth. The speaker is only expressing a weak possibility.

It must rain

This is so strange and incorrect, You can't oblige the sky to rain.

It might rain

It expresses a weaker probability, there is more reserve or doubt on the part of the speaker

In this case, I think It might rain and It may rain are the best way and most polite.

can is generally used to skills, ability and things safe (e.g. He shot to me, I can to die).

  • 1
    @MADY - It's usually a good idea to wait a little while rather than immediately accepting the first answer! In this case, I think "It can rain" is very awkward and not idiomatic-sounding. Can just expresses ability. Of course it can rain - it always "can" rain. But only "it might rain" expresses a possibility related to the clouds.
    – stangdon
    Sep 1, 2016 at 19:01
  • I got it! Another answer could be "may" and "could", right?
    – MADY
    Sep 1, 2016 at 19:29
  • Why -1? I think my answer is correct.
    – Mattew
    Sep 1, 2016 at 19:33
  • @MADY You can use may and could, Them are both correct.
    – Mattew
    Sep 1, 2016 at 19:35
  • 2
    None of these usages are "polite" or "impolite." It's impossible to be either one when talking about the rain. Also, we would never say "He shot to me" or "I can to die." @Mattew , please learn more about when to use the bare infinitive (hint: some verbs require it.) Also, "can is generally used to skills" is hard to understand. Did you leave out a verb, maybe? Sep 1, 2016 at 22:24

From a comment by P.E. Dant:

The answer to your exercise question is "might." Here is a dictionary definition of this modal (or auxiliary) verb. It is used here to express possibility. None of the other choices make any sense. "Must" makes no sense, since "must" expresses obligation, and although farmers wish they could, no-one can force the clouds to rain. "Can't" makes no sense for the same reason that "can" makes no sense.

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