I remember someone asking a similar question and it was answered but I forgot where I found it and so... yeah I'm going to ask again. :D Is "Is e..." used when the "it" has a definitive particle ("an") and "Is ... e" used when the "it" does not have a definitive particle? Because I remember back in Basics 1, there was "Is fear e" and sentences that use the "Is...e" instead of "Is e...".
That's the case, but remember the definite article [an] won't be there where there is a phrase in the genitive case: e.g. 'Is é namhaid an phobail é' = He's an enemy of the people; where the final é refers to him, and the first é is there because 'namhaid an phobail' is definite but in the genitive case, so loses the first 'an'.