Passives in English grammar are words that express the passive voice.
Passive is a grammatical function.
The grammatical form that can function as the passive in English grammar is the verb phrase. The two auxiliary verbs that can function as the passive are the verbs be and get.
Passives are constituents of the verb phrase.
Brinton, Laurel J. & Donna M. Brinton. 2010. The linguistic structure of Modern English, 2nd edn. Amsterdam: John Benjamins Publishing Company.
Hopper, Paul J. 1999. A short course in grammar. New York: W. W. Norton & Company.
Huddleston, Rodney. 1984. Introduction to the grammar of English. Cambridge: Cambridge University Press.