My name is Wu Xing. I'm twelve and I'm in class 2, Miss Tang's class. She is my English teacher I like geography best (最) because it always tells stories about different places. And I often read books about geography. Today, there is a sale on in the bookshop near my school I'm choosing books here.

    Yang Dao is my friend. He i6 twelve too and he is in Class 3, Miss Lu's class. She is his maths teacher. Yang Dao is good at computer science. He likes doing many things on the computer, such as reading books and choosing presents. Now he is drawing a tiger on the computer. It's his favourite animal. It's a present for his brother's birthday. The party is in the evening.

如图所示，在磁场中，一通电导线AB被弹簧悬挂着，在水平位置上处于静止状态，当开关断开后，则（　　）