This paper introduces the three distinctions on language made by Saussure,Chomsky and Halliday respectively and compares their emphases and significance.

• 通过分别对索绪尔、乔姆斯基和韩礼德语言和言语、能力和表现、语言潜势和语言行为三对概念的介绍和比较,认为索绪尔侧重研究“语言”,但不忽视“言语”对“语言”研究的作用;