阅读文章，回答下面问题

　　Mrs. Green is the mother of two children. She is a shop assistant(店员). She is very busy every day. Every morning, she cooks breakfast for her family. She cooks eggs for her daughter and makes bread for her son. At noon she eats hamburgers in her shop. Her children have lunch in the school dining hall.

    In the evening, Mrs. Green gets home very late. When she gets home, her children get ready for dinner. Mr. Green cooks beef noodles for his daughter and cooks carrots for his son. And Mrs. Green usually buys some chicken from the supermarket. It's Mrs. Green's favourite food.

某实验小组按照课本要求探究并联电路中电流的关系，他们设计的电路如图所示。把电流表分别接入到电路中的A、B、C处，测出它们的电流，填入下表：

①根据电路图，完成连线____；

②通过对上面数据的分析,可以得出结论是:____；

③测量三次的目的是：____，在实验中我们可以采用____的方法改变电流的大小从而进行三次实验；