lucy24 - 7:28 am on Jul 7, 2011 (gmt 0)
It's not totally clear what you mean by "word". Do you mean "a pair of free-standing letters"? Most RegEx dialects would say
where \b simply means "word break". Is there any possibility of numerals or lowlines adjoining the letters? Those count as "word" characters, so you'd have to exclude them too.
Is that apostrophe in "'an" intentional? That is, your intended match is 'an ?
Is this what you're trying to match?
(you can't see the space but in most RegEx flavors it's just another character ;))