It could potentially be the subject of a sentence, if that is what you mean.
the subject is "You understood".
Everything that is not part of the subject is the predicate. Subject = 'You'. Predicate = 'ordered breakfast from room service.'
Subject, "they", verb, "entered", direct object, "room", (and "the" is an adjective of room). So subject verb direct object.
The subject in the sentence "The queen dusts the room" is "queen." She is the doer of the action of dusting.
You can be a subject in a sentence You should go and see the new movie by Peter Jackson. In imperatives, e.g. "Clean your room.", you is an implied subject. "You clean your room."
"man"
Subject: "There." Verb: "may be"
Joanna Ruth Fuller has written: 'Surgical technology' -- subject(s): Operating Room Nursing, Operating Room Technicians 'Surgical technology' -- subject(s): Accessible book, Operating room nursing, Operating room technicians, Surgical technology, Operating Room Nursing, Operating Room Technicians
The simple subject is "youngsters".
Shirley M. Brooks Tighe has written: 'Instrumentation for the operating room' -- subject(s): Atlases, Surgical Instruments, Operating room nursing, Surgical instruments and apparatus 'Fundamentals of operating room nursing' -- subject(s): Operating room nursing
I think it is Was and Cleaning.
you