Object-oriented analysis (OOA) is a semiformal specification technique for the object-oriented paradigm. Object-oriented analysis consists ofthree steps. The first step is (6) . It determines how the various results are computed by the product and presents this information in the form of a (7) and associated scenarios. The second is (8) , which determines the classes and their attributes, then determines the interrelationships and interaction among the classes. The last step is (9) , which determines the actions performed by or to each class or subclass and presents this information in the form of (10) .

A．use-casemodeling

B．classmodeling

C．dynamic modeling

D．behavioralmodeling

图甲是小刚测动滑轮的机械效率的示意图.他用弹簧测力计拉动绳子自由端，将重为6N的钩码从A位置匀速提升到B位置，同时弹簧测力计从图中的A'位置匀速竖直上升到B'位置，在这个过程中，弹簧测力计对绳的拉力为F，弹簧测力计的示数如图乙所示则：

（1）弹簧测力计的示数是_______N；

（2）弹簧测力计移动的距离为________cm；

（3）滑轮组做的有用功是_________ J