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（）.

The first step is（）.

A．use-case modeling

B．class modeling

C．dynamic modeling

D．behavioral modeling

传染性单核细胞增多症临床表现多样化，主要的临床表现有（）

A.不规则发热、伴畏寒，热程数日至数周不等

B.浅表淋巴结肿大、压痛

C.咽部充血水肿、疼痛

D.肝脾肿大

E.可出现皮肤斑疹、丘疹，皮肤出血点或猩红热样皮疹