Dear Teacher,<br/><br/> I have understood more about subject complement through your help. Thank you. I have four sentences:<br/><br/> Whose raincoat is this?<br/><br/> What doctors are vollunteers?<br/><br/> Which person is John?<br/><br/> What person is John?<br/><br/> Are the interrogative pronouns subject complements?<br/><br/> Please explain carefully.