In Michael Swan's Practical English Usage, fourth edition, entry number 86, entitled 'typical behaviour, can, could, may, might, will, would', I found this example sentence:

Sulphuric acid will dissolve most metals.

Would it be possible to say or write 'Sulphuric acid can dissolve most metals. ? Is there a difference between the two?

  • That statement means that sulphuric acid will dissolve a metal IF it comes into contact with it. It's not saying that the acid is going to come into contact with it. Therefore all it's saying is that it CAN dissolve the metal if it comes into contact with it. Replacing "will" with "can" will pretty much mean the same thing. That's not to say that the words "will" and "can" have the same meaning, but in this context it's as I explained.
    – Zebrafish
    Jul 31, 2018 at 3:48
  • Will here is about "behavior;" can is about property/capacity/capability. They can mean different things in different contexts.
    – Kris
    Jul 31, 2018 at 12:46

1 Answer 1


Dogs can bite you. That doesn't mean that they always will bite you. (In fact, they seldom do.)

However, sulphuric acid not only can dissolve most metals that are exposed to it but always will do so (if given the chance).

  • Q: What can dissolve this metal? A: Why, sulphuric acid can! versus Q: What will happen if I pour sulphuric acid on this metal? A: Why, it will dissolve the metal! Jul 31, 2018 at 0:57
  • How about "Some sharks will eat men"? Like the dogs, they can eat men, but won't always do it… and the use of "will" in the sentence is still correct, and of common use, I think…
    – user58319
    Sep 22, 2018 at 17:29
  • @user58319 Quite right. And some dogs, especially rabid dogs, will bite you. The more their nature is towards biting, the more applicable the statement is. But can and will do still mean something different. Sep 22, 2018 at 18:32

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