what is the difference b/w could & can

[Cool Boy]

Hi everybody ,

First of all thanks for creating such a nice plateform .

My question is : What is the difference between can and could . Some year before , I was in a immpression that could is past tense of can . But now I am sure that there is something more also . people use could for present tense also .
for example , could you please repeat this .

please clear my confusion .

thanks a lot .

[zhouai]

The first point,could is past tense of can;
The second point,used to indicate ablility,possibility,or permission in the past;
The third point,used with hypothetical or conditional force:
The fourth point,used to indicate tentativeness or politeness:

[zhouai]

Or you can find out the difference in an English-English dictionary.

[GiddyGad]

The point is that in English the Past form is not only used to refer the said to the Past. It also may soften the statement, make it less insistent, less declarative. The said doesn't only concern the modal 'could'. It's general and is called the Subjunctive Mood. Here are some examples: "It's time we had a snack"; "It's important that parking spaces and pathways (should) be constructed"; "...as if civilization were about to jump the seas to its next manifestation..."; "I wish I had a friend like you" et al.

Thus, the Past form may express the Past and the Present,
and Modal verbs in the Past may express the Past, the Present and the Future in the Subjunctive. It seems evident since there's no form to express the Future. (Modal verbs are verbs that express the attitude of the speaker to what he says).

[Guest]

Hi everybody ,

First of all thanks for creating such a nice plateform .

My question is : What is the difference between can and could . Some year before , I thought that could is past tense of can . But now I know that there is something more also . people use could for present tense also .
for example , could you please repeat this .

please clear my confusion .

thanks a lot .

http://www.englishclub.com/grammar/verb ... _can_1.htm
http://www.englishclub.com/grammar/verb ... _can_2.htm

[Guest]

Summarize the two links above:
Can is an auxiliary verb, a modal auxiliary verb. We use can to:
-talk about possibility and ability (what we are able or free to do. Normally, we use can for the present. But it is possible to use can when we make present decisions about future ability.)

-make requests (We often use can in a question to ask somebody to do something. This is not a real question - we do not really want to know if the person is able to do something, we want them to do it! The use of can in this way is informal mainly between friends and family)

-ask for or give permission (ask or give permission for something. We also use could, may, might for permission. The use of can for permission is informal.)

Could is an auxiliary verb, a modal auxiliary verb. We use could to:
-talk about past possibility or ability (We use could to talk about what was possible in the past, what we were able or free to do. We use could (positive) and couldn't (negative) for general ability in the past. But when we talk about one special occasion in the past, we use be able to (positive) and couldn't (negative).)

-make requests (We often use could in a question to ask somebody to do something. The use of could in this way is fairly polite (formal))

[Cool Boy]

Could is past tense of can, but both words convey slightly different meaning. Look at the foll. sentences:
1. I Can do it.
2. I Could do it.
The first sentence conveys More suriety than the second one. I Could do it is as good as,I Possibly, (maybe) could do it. Here the person is not sure of whether he could do it, wheras I Can do it is full and final wording.

I am understanding your example but can is used for uncertinity only , I mean if a person is sure then he will use " I will do it " .

[Cool Boy]

The second point,used to indicate ablility,possibility,or permission in the past;

The third point,used with hypothetical or conditional force:

The fourth point,used to indicate tentativeness or politeness:

could you please be clear , what is you talking for . Thanks . Can you explain your point in simple example form .
Thanks again .

[GiddyGad]

Hi Cool Boy,
inquisitive, ain't ya?

Good. Let's try and see all the modals as 5 pairs of Past vs Present forms: might/may, could/can, would/will, should/shall, and must(no Past form)/ought to(no Present form). Some grammars mistake other verbs (e.g. dare, need, etc.) for modals, but these verbs don't fit in. Forget them.
You may place these verbs on a scale according to the degree of certainty on the one hand and according to the degree of, as it were, insistence on the other. So you will have two scales having the same look:

might->may->could->can->would->should->ought to->must->will->shall

the past time forms will lessen the degree of certainty/insistence, unless they express the Past time.

NB If you find it difficult to comprehend how the Past time form should fail to convey the Past just imagine bygone as bygone that lives only in your memory you can't rely on; what will be is not a fact until it is; what you can be sure of is only what is.

Thus while the Past forms of all modal verbs can refer the events to the Present, the Past, and the Future (with a certain degree of certainty/insistence) the Present forms have to do with the Present and the Future only.
Mind that the verbs "will" and "shall" do not necessarily refer the events to the Future and aren't linked to the category of Person, e.g. "The trees(3rd prsn) shall be planted regularly" (instruction); "The applicants will have good English language command" (requirement); "The plaza might prove too hot and barren were it not for a planter filled with four magnificent pines".

Here is an excerpt from a tale by a well-known English writer Eleanor Farjeon, where the verb "will" has four different meanings:
... the Cook came up [to the King] and gave notice.
'Why?' asked the King.
'Because do what I will, the kitchen fire will not light,' said the Cook, 'and if the kitchen fire will not light, I will not stay.'
Here only the last use can be referred strictly to the Future.

Your questions?