"The years"

[anya_mz]

what's the difference here? both "annees" and "ans" are correct.

[Thrissel]

Another summary here
http://french.about.com/od/vocabulary/a/an-annee-jour-journee-matin-matinee-soir-soiree.htm

[RKSMT]

Id read this before, which is why I only put, Les annees, instead of that and, Les ans. Ans, is used when saying for example, it took me three years to finish, not, it took me years to finish. When you say, the years, its like my last example, a duration example. So, the years, should be only, Les ans, correct?

[maartenvg]

They talk about it here: http://forum.wordreference.com/showthread.php?t=9547

[djbrubacher]

So how can they both be right? I've read all of the references, but this is not a date, there's no adjective, it's doesn't make any reference to "during, or passing time", so why isn't just "Les années" correct. I truly do NOT understand this.