I was recently asked a very good question by a Chinese friend who teaches english as a second language and I can’t even think of the answer myself :-[
Can someone please explain the differences between can/could and also may/might.
The example he used was "the phone is ringing it could be your mother" Why can’t "can" be used here?
When I consulted the dictionary it said that could is the past tense of can and might is the past tense of may.
Maybe I’ve been using colloqiual language for too long as I can’t find any definate differences but instead only seem to have an instinctual grasp of the words.
Also around these parts it is common to use might for such sentences as "it might rain/she might call" instead of the more formal sounding "it may rain" etc. which adds to my inability to clearly explain.
These words are called auxialiary verbs and modals in English grammar.
This Spanish site goes into great detail about the technical function of modals in English, and probably will give you more information than you can remember, but I found it very interesting nonetheless:
Strictly speaking, can operates in the present tense, could in the past tense, and similarly for may and might. But in practice, we hear all these words operating in the present tense very often in everyday speech, as a means of diffusing the directness of the statement or question.
From the above referenced site,
Ability and possibility are similar ideas. If you’ve got the ability to do something, then it’s possible for you to do it - in principle at least, although there might be something that prevents you. And, conversely, if you haven’t got the ability to do something, then it isn’t possible for you to do it. Both can and could (and other modals, especially may and might) are used to express various kinds of possibility, ability, permission and potential.
I think that sums it up, but definitely read the sites for more. They’re both quite informative.
‘can’ implies the ability to do something - i can go shopping, because i have money, free time and i can walk, drive and lift things off shelves. ‘could’ implies a number of different possibilities, or some uncertainty as to whether something is possible or needs to happen - i could go shopping if the film finished early, i could go shopping if we have no milk left. it also suggests that something would be possible but something temporary is preventing it - i could go shopping if it wasn’t for the thick fog.
i haven’t got any evidence for that - it’s just my opinion. hope it helped!
As an addendum, I should like to point out that I’ve encountered copious citations of may and might (predominantly the latter) in final clauses in Frankenstein, by Mary Shelley.
"Abhorred monster! Fiend that thou art! The tortures of hell are too mild a vengeance for thy crimes. Wrteched devil! You reproach me with your creation; come on, then, that I may extinguish the spark which I so negligently bestowed."
Indeed, ability versus permission is the best general way of differentiating between these words, although when you ask "Can I do this?" and another replies "Yes you can", then this is permission, in which case substituting Can for May, is generally recognized as being a more polite way of speaking.
We say, "It can’t be," as likewise to mean, "It isn’t possible!" So, "It can be your mother," stands to be rendered, "It’s possible to be your mother," even though your incipient affirmative falls well below acceptable norms, distinctly related to English speech & communication—in other words, "pure trash!" But clinical semantics will furthermore admit, "It’s permitted to be your mother," or, "She (your mother) is allowed call"—as modal "can" may also take the sense of introducing, what is clearly allowed or permitted: e.g. "You can do that (i.e. it’s permitted)!"
With regards to "could" in said context, "It ~ be your mother," although defined until now as past tense, it looks more like a conditional preterit here, which in turn loses all real tempus or "time" as subjunctive modal, while assuming a hypothetical role that completely rules out any negation, thus to find use primarily for the sake of courtesy: hence the metaphrase, "It’s possible to be your mother, and not impossible that it’s the same!"
I definitely hear them as distinctly different, intrinsically… Not that everyone uses the two phrases distinctly, mind you, but that to me they are different.
Take, for example, a hypothetical advertisement for a charitable organization collecting funds for assisting orphaned children. "Can you help?" This sounds perfectly acceptable. "Could you help?" That would just sound silly.
In my opinion, the reason we hear so many people using "could" when they should be using "can" is because they are implying the conditional.
"Hey man [if I may be so impertinent as to ask], could you spare a buck?"
I know this is just my opinion, and I don’t expect it to be a popular one. ;D
Give yourself a gold star for courage, Tim m’boy, conditional tenses have always proved difficult to comprehend, no matter what in grammatical analysis, and nearly impossible to teach! In this respect, I understand ol’ "Frank" reads Plato’s Cratylus before his class in the original Greek; you could try needling him for help in the optative & subjunctive moods, a lesson more advanced than anything found in the conspicuously decadent, English paradigm.
[quote author=bandito link=board=grammar;num=1112267754;start=15#15 date=04/17/06 at 13:45:08]Give yourself a gold star for courage, Tim, conditional tenses have always proved difficult to comprehend, no matter what in grammatical linguistics, and nearly impossible to teach! In this respect, I understand that "Frank" reads Plato’s Cratylus before a class in the original Greek; you could try needling him for help in the optative & subjunctive moods, a lesson more advanced than anything found in the English paradigm.
Oh I see, you think Tim is some novice, so that explains it. See Tim is an expert who speaks English perfectly. Btw obfuscatorial language is the hallmark of those who want to appear intelligent, not being obfuscatory is not being stupid, it means he can speak with anyone, and be understood.
You might first do the intelligent turn and ask Tim himself, if he thinks I called him stupid, then point out exactly where I did so, because I cannot find it anywhere—likewise, go shopping for some new epithets, thou abominable cretin, because your seismically tactful style exhibits all the linguistic eloquence of King Kong himself, the undisputed lord of literary bombast!
