题目

“If you have not played video games, your childhood should be called 'incomplete'.” That's from Zhan Zaozao, 29, the screenwriter（编剧）of Play to Grow Up, a 40-minute short movie. It tells the story of two men growing up fans of video games and how they find happiness in games. While people think playing games makes one lazy and is a waste of time, Zhan tries to prove that one can make a living out of it. In the movie, the two heroes, Dunzi and Yanjing, who are in middle school, visit a video games room on the street each day after school. But why make a short movie about vid如图所示，在菱形ABCD中，点E，F分别在CD，BC上，且CE=CF，求证：AE=AF．