一位高等学校语言学教师在讲到语言的约定俗成原则时举了两个例子,说汉语的“拍马屁”不能换说成“拍牛屁”“拍狗屁”。相反,“放狗屁”也不能换说成“放马屁”“放牛屁”“放猫屁”等等。学生听后哄堂大笑。这两个例子虽然有些不雅,但是用来说明语言的约定俗成原则和部分的无理据性倒是十分恰当的。从教学法角度说,将一门很容易讲得枯燥乏味的语言学课程变得引人入胜,这也是无可指责的。在本文中我们想补充指出,这两个例子也能很好地说明语言的民族性。西方人很爱狗,有一位美国语音学家在他的一本语音学专著的扉页上写道“献给我的狗”,这在中国人看来简直是不可思议。虽然英语中的dog有时也指“无赖汉”“坏蛋”“废物”,但是总的说来,英语中的dog给人的联想是好的,不象汉语中 A high school linguistics teacher cited two examples when it comes to the convention of language, saying that Chinese “flattery” can not be said to be “patting cow” or “patting shit.” On the contrary, “put shit” can not be changed to say “shit” “letting cow”, “let the cat fart” and so on. Students laugh after the concert. Although these two examples are somewhat indecent, it is quite appropriate to explain the conventions and the irrational part of the language. From a pedagogical point of view, it is beyond reproach to make an easy-to-read, linguistic course fascinating. In this paper, we would like to add that these two examples also provide a good illustration of the nationality of the language. Westerners love dogs. One American phoneticist wrote “Dedicated to My Dog” on the front page of one of his phonetics monographs, which is simply inconceivable to Chinese. Although dogs in English are sometimes referred to as “rascal”, “bad guy” and “waste,” but in general dogs in English are good associations, unlike Chinese