Are or do
Just heard a commercial that featured one of those odd uncoordinated coordinations that happens because English treats 'to be' as though it were an auxiliary verb:
Are you between 55 and 80 or know someone who is?They're trying to coordinate two questions, and generally we omit the second auxiliary - but only when it's the same one as the first. But "know" takes "do" to make questions (and negatives) - as do all lexical verbs. "Be", however, doesn't* - in fact, "be" itself is its own auxiliary. "You know someone - do you know someone?" but "you are between 55 and 80 - are you between 55 and 80?"
So the perfectly coordinated construction - compare "do you watch television or know someone who does?" - falls apart.
* There are in fact plenty of Englishes that treat "be" as a lexical verb, with do-support constructions such as "Do you be between..." and "I do not be...", but Modern Standard English isn't one of them.