Hi,
Are these sentences correct?
I have been to Spain in the year before last.
I went to Spain the year before last.
Thank you.
The second sounds more idiomatic and is ["better grammatically."]
I went to Spain two years ago. (that's what I'd say).
I have been to Spain in the year before last. 
I went to Spain the year before last.
I have found a sentence on the internet:
I have been to XXX in the last year.
Is this is fine, why is that not?
I have been to Spain in the year before last.
If I change it to this: I had been to Spain in the year before last, is that acceptable?
If I change it to this: I had been to Spain in the year before last, is that acceptable?
No. If you want to specify the time when you did something, the sentence should use simple past tense.
If I change it to this: I had been to Spain in the year before last, is that acceptable?
Well, you could certainly have something like:
"I had been to Spain [in] the year before last, so when I went again last year I knew what to expect." That would work.
To answer your previous question, the reason why "I have been to XXX in the last year." sounds odd is that the perfect tense doesn't really work where you have a definite time specified. You'd need to say something like "I have been to XXX several times in the last year or two."
Thank you.
In this page, you can see the author said last year and in the last year are different.
http://www.englishpage.com/verbpage/presentperfect.html
In this link, read down to the NOTICE, you can find an pair of examples:
I went to Mexico last year.
I went to Mexico in the calendar year before this one.
I have been to Mexico in the last year.
I have been to Mexico at least once at some point between 365 days ago and now.
I have been to Mexico in the last year.
I have been to Mexico at least once at some point between 365 days ago and now.
Yes, I see the logic behind their choice of the perfect tense there. It just sounds a bit odd to me on its own, but then that's the problem with a lot of these textbook examples which don't include anything much in the way of additional context.
That's possibly why Parla marked it as wrong in post #3.
[...]
I have been to Mexico in the last year.
Just to add to the excellent explanations you have received, Stephen:
I have been to Mexico in the last year is fine because the time period specified hasn't ended.
This is not true of