I am learning Italian by using CDs. On the CDs it seems the use of "ed" is inconsistent. For example, sometimes the CD says "e adesso" and sometimes it's "ed adesso." I think that I am supposed to use "ed" the same way we use "an" in English, but now I'm not sure if that's correct. I know this is a small thing, but it is really irritating me. Is there a rule for when you use "e" and when you use "ed"?