我国著名的语言文字学家、教育家钱玄同,三十年代起一直担任北京师范大学教授。1936年,钱玄同在北师大中文系讲传统音韵学,讲到“开口音”与“闭口音”的区别,一同学请他举一个例子,他说——北京有一位京韵大鼓女艺人,形象俊美,特别是一口洁白而又整齐的牙齿,使人注目。女艺人因一次事故,掉了两颗门牙,应邀赴宴陪酒时,坐在宾客中很不自在,尽量避免开口,万不得已,有人 China’s famous linguist and educator Qian Xuan Tong has served as a professor at Beijing Normal University since the 1930s. In 1936, Qian Xuan-tung talked about the traditional phonology in the Department of Chinese at Beijing Normal University, talking about the difference between “opening tone ” and “closed accent ”, and one of the students asked him to give an example. He said - Beijing has one Beijing rhyme bass artist, handsome image, especially a white and neat teeth, eye-catching. Female artist for an accident, lost two incisors, invited to feast dinner, sitting in the guests are uncomfortable, try to avoid the mouth, as a last resort, some people