grammar question! conditional from future looking back to past?

Question

okay, here's 2 variants, tell me which variant is grammatically better and what is wrong with the other (if anything) or if nothing is wrong, why did you make your choice..
(1)if i were there, i could have done it
(2)if i had been there, i could have done it
if i were there, i would have done it
if i had been there, i would have done it

okay, sorry, i wrote this question wrong. what i really mean to say is which is better:
if i had been there, i could have done that
OR
if i were there, I could have done that

i understand if they're technically both correct but which one is better?

Answer 1

#2 is correct; #1 is incorrect.

You are dealing with conditional forms of the verbs, not the usual simple tenses (which are not really all that simple, as you know if you have ever taught English as a second or foreign language).

Second and third conditional are the forms you are dealing with here. Both deal with conditions contrary to fact--something that will not or did not happen.

Second conditional. If the condition contrary to fact is at the present time or in the future, here is the form you use:

If I were President, I would veto that bill (past tense for the condition, would/could auxiliary + verb for the result).

If I ate less, I might gain less weight.

For your #1 to be correct, you would say this: If I were there, I could do it.

Third conditional. If the condition contrary to fact is in the past, here is the form you use:

If I had been President, I would have vetoed the bill (past perfect for the condition, would/could/might auxiliary + present perfect verb for the result).

If I had eaten less, I might have gained less weight.

Your #2, therefore, is correct: I I had been there, I could have done it.

The choice among would, could, or might, of course, depends not on grammar, but on your meaning: would connotes determination (I would do it), could connotes ability (I could do it), and might connotes simple possibility (I might do it).

There are also first and zero conditionals. If you are interested in those or in more examples of second and third conditionals, see the site listed below.

Answer 2

You are really giving FOUR choices here, and I dont know why you are calling it TWO. But grammatically all four are correct,
and the choice depends on the meaning you are trying to convey. Grammar doesnt give you that answer, only common sense.

Answer 3

Well, would and could are interchangeable depending on the intended meaning.
But other than that, number two is the more correct.
Number one is saying in some type of present tense then past. If you had said "If I was there, I could have done it" then there would definitely be a debate between one and two.