The exact usages of could & would

[pc boy]

Hi everybody.
I need to know the exact usages of could & would,gramatically,formal & informal.especially in requests.
I was just wondering if you can help or give me a good source to find it.
any help is appreciated.

[Greight]

Hi,
Here is a good difference marker; I hope it can help. If after reading it thoroughly you had any more doubts just tell us.

This is a very common question and there seems to be a lot of confusion about what the difference is exactly between ‘would’ and ‘could’.


Let’s take a look at ‘would’ first:

‘Would’ for Unreal, Impossible or Hypothetical Situations
We probably see this most often in conditional sentences where we want to talk about a situation that is either not real or not likely to occur now or in the future. To do this we use a past tense of the verb in the if-clause and would + infinitive in the main clause. Have a look at these examples:

• If I knew how to speak French, I would visit France.
• If she traveled by train, she would arrive this afternoon.

Contracting ‘Would’
Don’t forget that you can contract ‘would’ and that you will often see it as:

• I’d like to visit her. (= I would like to visit her).
• They’d swim more often. (= They would swim more often)

‘Would Like’: Expressing a Desire for Something
OK.. that covers ‘would’ when we are talking about hypothetical situations but what if I say:

• I’d like a cup of tea, please. (= I would like …)
• She’d like a Tomato Salad. (= She would like …)

Here, ‘would‘ is used as an auxiliary for the verb ‘to like‘ and takes on a special function of expressing desire for something. Notice that you cannot use ‘could‘ in this way.
‘Would Have’ to talk about something in the past that did not happen
Now, if we want to talk about something in the past that did not happen, we usehad + past participle in the if clause and would have in the main clause. Look at these examples:

• If Simon had taken his passport, he wouldn’t have had a problem buying his ticket.
• If Jenny and Max had remembered Mary’s birthday, she wouldn’t have been angry.
• If I had lived in Australia I would have learned how to surf.

Hope your staying with this Mahesh - it’s a long posting as it has to cover quite a bit of territory so that you can really see where the differences are!


Now, lets look at ‘could’.

Could: Permission, requesting and expressing ability
We can use ‘could‘ to ask for permission, to express a possibility, make a request or express an ability to do something. Look at these examples:

• Could I borrow your car this evening? Mine is being repaired.
• You could take the train. Then you won’t have any problems parking.
• Yes, I could but I don’t know where the train station is.
• Jonas could play the violin very well by the age of five.

‘Could Have’ to talk about hypothetical actions in the past that did not happen.
Until now I think the distinct usages of ‘would’ and ‘could’ have been pretty clear but here, with ‘could have‘ I’m afraid we are moving into an area where ‘could have’ and ‘would have‘ are very similar!
Like would have, (and should have … which we are not covering in this posting),could have can be used to talk about past hypothetical actions - things we did not do or other did not do or didn’t succeed in doing. For example:

• I could have gone to university if I had had better results at school.
• I would have gone to university if I had had better results at school.

Now, in terms of meaning we are going to have to dig deep to find a distinction between the two but in the first example, ‘could have’ expresses an ability to have done something if the condition (getting better results at school) had been met. ‘Would have’ expresses a clear intention to have done something if the condition had been met - that is not just the ability to do it but also the intention to do it. Complicated I know but if you think through the examples I hope you will notice the difference.


Source: english4today.com

[pc boy]

Dear Greight,
first of all I'm gonna thank U alot for your clear explanation.
but I'm afraid to say that I'm absolutely convinced that the usages of would & could are more than what you've told us.
look at this:
would you give me a hand?
why would I come back here?
the meaninigs are damn clear but I'm looking for the rule which the words have been used under.
besides I was not looking for distinctions between these two words.I wanna know the exact grammatical rule that shows how & where u can use these words.
BTW I can't help my hands writing THANK YOU ALOT again.
Sincerely
Your Friend

[Greight]

Dear friend

I think the above post was clear enough but for the very examples you provided I can not find any strict grammatical rule forcing us to use either would or could. Instead what seems to have a role is the meaning. When you use could you are focusing more on the ability while when you use would the emphasis would be on willingness. These meaning differentiation exactly applies to your examples.

[pc boy]

I think you're really great.
TNX pal.

[Greight]

Hey, I'm flattered .
You're welcome.

[rezafo]

Hi,

Having read all the posts, I felt putting this:

would you give me a hand?

[Reza: would you give me a hand? Rosa: I wish I could! ]

[Rosa, if you were allowed and if you could, would you give me a hand?]

Now let's replace it with "could"

Could you give me a hand? [ apart of a polite request; could I borrow your pen for a while?]

[Rosa, what would you do if you were in my friend's shoes in that situation? When you are not allowed and when your help will get you in trouble, yet, would you give me a hand?]

Here, in this your sentence, "would" denotes the intention and possibility of something to happen in an imaginary situation. It's a matter of intention not the ability.

why would I come back here?

This one is simple. You can't easily replace "would" with "could", because it reads as "why could I come back here? , although this one implies your asking the necessity and need of "coming back" but it's referring less to the intention arising by using "would".

We naturally less stick to the rules and more we speak the most common and conventional structures we read and listen here and there. That's why we are encouraged to read and listen as much as we can. Not to forget that on some tests, we have to know the delicate differences between words and phrases and this is where we are to abide by the rules!


Please comment and correct me if I was wrong.

[Greight]

I think what you posted confirms what I posted