He can be in class.

K

kira_moondance

Senior Member
Vietnamese
Modals: deductions about the present
According to the website above, when we want say that we think something is possible but we're not sure, we can use might, may or could. I'm wondering why we can't use can.

For example, instead of saying, "He's not answering. He could be in class," can we say "He's not answering. He can be in class"?
 
    • As the link shows, the negative "can't" is used to show we deduce that something isn't possible, but "can" isn't used to deduce that something may be possible.

    It can't be him; he's in China.
    It could be him; he came back yesterday.
     
    I read somewhere that "can" is used to show what is possible in general while "could" is used to show what's possible in specific cases. I can't find the source of that information. But is it why "can" isn't used to deduce that something may be possible?

    I know that for native speakers, you just don't use "can" that way. But for me, a non-native speaker, knowing the reason behind some rules makes it easier for me to remember how to use certain grammar structures.
     
    kira_moondance said:
    Thank you for your replies. What I wanted to ask was why we can't use "can" in that case while "could" is possible.
    Click to expand...
    Because "He can be in class" has a different meaning. It means "It is physically possible and permissible for him to be in class". So we can imagine: Teacher: Can John be in class this Monday? Is he well enough? Parent: No, he's still unwell, but he can be in class next Monday, I think, if the doctor agrees.

    I.e. He will be physically capable and have the doctor's permission. It doesn't mean maybe. "I don't know where he is, he could be in class" means "Maybe he is..."
     
    Keith Bradford said:
    Because "He can be in class" has a different meaning. It means "It is physically possible and permissible for him to be in class". So we can imagine: Teacher: Can John be in class this Monday? Is he well enough? Parent: No, he's still unwell, but he can be in class next Monday, I think, if the doctor agrees.

    I.e. He will be physically capable and have the doctor's permission. It doesn't mean maybe. "I don't know where he is, he could be in class" means "Maybe he is..."
    Click to expand...
    Thank you so much for clearing that up. I just realized we use the same word in Vietnamese to refer to both of those cases so it's a bit confusing for me.
     
    I don't find Keith's example very convincing, I'm afraid.:)

    Positive "can" is also used in the sense of "sometimes":
    "It can be very cold here in December." Here, the negative form would not be used, since it has nothing to do with a logical deduction.

    He can be a nuisance in class. (Sometimes he is a nuisance in class).
    No, he can't be a nuisance in class. He's a very quiet student. (No, it isn't possible that he is a nuisance in class.)
     
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