请以“动物”为话题写作文，题目自拟，除诗歌外文体不限，不少于600字。

如图所示，一个有界的匀强磁场，磁感应强度B=0.50T，磁场方向垂直于纸面向里，MN是磁场的左边界．在距磁场左边界MN的1.0m处有一个放射源A，内装放射物质 （镭）， 发生α衰变生成新核Rn（氡）．放在MN左侧的粒子接收器接收到垂直于边界MN方向射出的α粒子，此时接收器位置距直线OA的距离为1m．

小小玩具店。

     小虎85元                   小乌龟30元                        小鱼23元                    小绵羊40元

      This summer I will leave the junior high school where I have been for three years. I am generally considered to be a careful and polite boy now. However, five years ago, I was a little bit bossy(专横的). I often fought with other boys and sometimes I even fought with my elder sister. When I saw Superman on TV for the first time, I dreamed of being a superman one day.
    One P.E. class, I called up all of my friends to get together in our classroom. “Can anybody jump out of the window?” I asked them. After hearing this, all my friends kept silent. “I know you are all chickens,” I said. “Can you?” one of my friends asked me. “Sure!” I answered. “If I do it, I will get all the toys that you have. If I fail, you will get all of my toys, OK?” They said, “OK!”
Then I went up to the window of the second floor. I took a deep breath and then jumped down, stretching out my arms just like Superman. Then I hit the ground.
     When I opened my eyes, I found myself lying in the hospital. I was taken to the hospital because my arms were badly hurt. Later, I heard that my P.E. teacher nearly lost his job for this, but I never received the serious punishment I feared.