She was supposed to be elated.
 
I would disagree that "is supposed" is a passive construction in this
sentence, if for no other reason than intuitively I would say there is no
hidden agent;  nothing "supposed" her.
 
I agree that "supposed to" is one of many quasi-modals, as linguists have
often called them, in English.  Note that many people will use "supposed
to" in fragment form, indicating that the two words are bound together
probably as a single morpheme.  For instance, I've often heard people
respond to a question about why somebody has to do something with "I'm
supposed to."  I don't see that this fragment would be acceptable if "to"
were an infinitive linked w/ "be" rather than "supposed".
 
Larry Beason,Director
English Composition Program
Dept. of English
Eastern Washington University
Cheney WA 99004
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