Are you a student? = eres un estudiante? Is he at the library? = esta el en la biblioteca? Are they construction workers? = son ellos trabajadores de construccion? Am I sick? = estoy enferma/enfermo?
@ Irene -Are we play tenis? > Do we play tennis? -Is he read the book? Does he read a book? Is he reading a book? Are you sleep? > Are tou asleep? Are you sleepy?