说明：  运行程序，显示屏左上角方出现一个小球，当单击动画工具按钮时，小球开始下落，最后停在地板上，再次单击动画工具按钮，动画结束，屏幕定格
(Run the program, display the top left corner of a square ball, when the button click animation tools, the beginning of the whereabouts of the ball, the last stop on the floor, once again click the button animation tools, animation ended, the screen frame)