吃掉午饭的生物老师

The science teacher lecturing his class in biology said, “Now I'll show you this frog in my pocket.” He then reached into his pocket and pulled out a chicken sandwich. 　　He looked puzzled for a second, thought deeply, and said, “That's funny. I distinctly remember eating my lunch.” 　　老师正在给学生上生物课：现在，我将要给你们看我袋子里的这只青蛙。接着，他把手伸进口袋，却拿出了一份鸡肉三文治。老师满脸困惑地看了一眼，沉思了一会儿，说道：真奇怪。我明明记得我已经把午饭吃掉了。