Notice that the relationship between the rhetorical is and the grammatical is is basically the relationship between what Jakobson calls the "poetic function" and the "metalingual function."

注意下,修辞学上的is和语法中的is之间的关系,基本上就是雅各布森所说的,“诗功能“和“元语言功能“之间的关系“

耶鲁公开课 - 文学理论导论课程节选