Possible Duplicate:
Use of “a” versus “an”
I have always been using a established.
The CPM is a established theory that explains.........
But when reading print material, I sometimes find an established being used:
The CPM is an established theory that explains.........
My English teacher taught me to apply a/an based on how the word sounded. Is that a/an established principle?
Relatedtab as I was typing up my question, somehow that does not work because after I posted the question, theRelatedtab changed and came up with really meaningful "related" questions that were dealing with the same topic. I will raise this on the meta as I have seen this happening a lot of late on other SEs are well. – May 28 '11 at 16:41