选择题 .  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     71    . It determines how the various results are computed by the product and presents this information in the form of a     72    and associated scenarios. The second is     73    , which determines the classes and their attributes, then determines the interrelationships and interaction among the classes. The last step is     74    , which determines the actions performed by or to each class or subclass and presents this information in the form of     75    .71.