一、语段等级与翻译单位等级(rank),亦即语法单位(grammaticalunit),是英国语言学家哈利迪(M.A.K.Halli-day)在系统语法(Systemic Grammar)中提出的一个概念,指的是语法的表层结构,也就是语法单位的层次排列。系统语法认为,语言通常有五个语法单位,或五个等级,它们由高到低可分为句子、子句、词组、词和词素。这些单位之间存在着级阶关系(rankscale),即高一级的单位由低一级的单位组 I. Grading and Translation Unit rank, or grammatical unit, is a concept put forward by the British linguist MAK Hall-day in Systemic Grammar. It is the superficial structure of grammar, that is, the hierarchical arrangement of grammatical units. System grammar that the language usually has five grammatical units, or five levels, they can be divided into high to low sentences, clauses, phrases, words and morphemes. There is a hierarchy of ranks among these units, that is, higher units consist of lower units