在图（a）所示的电路中，电源电压为12V且不变．电阻R₁的阻值为20 Ω，滑动变阻器R₂上标有“50Ω 2A”字样．闭合开关S，电压表的示数为4V．求：

（1）电流表的示数．

（2）电阻R₂连入电路的阻值．

（3）若移动滑动变阻器滑片P到某位置时，发现两电表中有一个表的指针如图（b）所示．小明和小华两位同学通过分析、计算分别求出了此时电流表和电压表的示数，他们的分析、计算过程及结论如下表所示．

（4）小明和小华的分析、计算过程及结论，有一个人是错的，请通过计算简述理由．

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）处填（）。

A. static modeling

B. dynamic modeling

C. use-case modeling

D. behavioral modeling