Object-oriented  analysis  (OOA)  is  a  semiformal  specification  technique  for  the object-oriented  paradigm. Object-oriented  analysis  consists  of  three  steps. The  first  step  is （）. It  determines  how  the  various  results  are  computed  by  the  product  and  presents  this information in the form of a （）and associated scenarios.The second is （） ， which determines the classes and their attributes， then determines the interrelationships and interaction among the classes.The last step is（）， which determines the actions performed by or to each class or subclass and presents this information in the form of（）.