Equivalence can be pided into two kinds: formal correspondence and functional equivalence. As the term suggests, formal correspondence is the equivalence at the level of form. Nida (1964) says that formal correspondence focuses attention on the message in form. One is concerned that the message in the receptor language should match as closely as possible the different elements in the source language. Nida calls the kind of translation guided by formal correspondence a “gloss translation”, which aims to allow the reader to understand as much of the source language context as possible. It attempts to render the exact word from source language to target language. On the other hand, functional equivalence follows the principle of equivalent effect, that is, the relationship between the receptor and the message should aim at being the same as that between the original receptor and the source language message. It attempts to render receptor words from one language to another, and caters to the receptor’s linguistic competence and cultural needs.   As Doctor Nida (2001) views, “in general it is best to speak of ‘functional equivalence’ in terms of a range of adequacy, since no translation is ever completely equivalent. 源/自:751:`论~文'网www.751com.cn A number of different translations can in fact represent varying degrees of equivalence”. Formal correspondence sometimes distorts the grammatical and stylistic patterns of the target language, and hence distorts the message, only to cause the translation to be ambiguous or awkward. However, functional equivalence sometimes changes the form of the source text, but preserves the message of the source language, because it transforms the message in the receptor language. Of the two, Doctor Nida undoubtedly favors the latter. “If a more or less literal correspondence is functionally equivalent in both designative and associative meaning, then obviously no adjustments in form are necessary. But if this is not the case, the translators should make some adjustments in order to achieve the closest natural equivalence”. This implicates that functional equivalence is actually supplementary to formal correspondence.  The concepts of formal correspondenc  e and functional equivalence also have attracted many other translation theorists’ interests. Peter Newmark puts forward his famous theory about semantic translation and communicative translation. “Communicative translation attempts to produce on its readers an effect as close as possible to that obtained on the readers of the original. Semantic translation attempts to render, as closely as the semantic and syntactic structures of the second language allow, the exact contextual meaning of the original.” “Admittedly, all translation must be in some degree both communicative and semantic….”(Newmark, 2001). TAN Zai-xi is a follower of Nida’s functional equivalence theory. He says that translation consists in reproducing the source language message from meaning to style by rendering the closest natural equivalent in the receptor’s language. Translators are confronted, all the way through translating, with the conflicts of form and content, meaning and style, equivalent and identity, and so on, but the most important point in translation is the content of the message of the source language, therefore, the transference of form should give priority to the transference of message. Mona Baker, in her book In Other Words: A Coursebook on Translation offers a detailed list of conditions upon which the concept of equivalence can be defined. She studies equivalence at different levels—equivalence at word level, equivalence above word level, grammatical equivalence, textual equivalence and pragmatic equivalence.   The theory of functional equivalence in translation is a great contribution to translation theory in the 20th century. It not only influences the biblical translation in the United States, but also influences the exploration on translation theory in China. According to the traditional Chinese translation theory, the translators should achieve “faithfulness, smoothness, and elegance”. But there are no how-toes towards meeting these three principles. Nida’s theory on functional equivalence leads to the heated argument in Chinese translation field which results in the benign circulation in development of our own translation theory. In this sense, Nida’s theory on functional equivalence is an important guidance to the practice of Chinese translators.    汉语科技文本翻译功能语言学视角(2):http://www.751com.cn/yingyu/lunwen_58109.html