Here are three main rules which are skopos rule, coherence rule and fidelity rule: the first one is the Skopos Rule. The action of translation has its purposes, and the word “Skopos” is a Greek word for "aim" or "purpose", and used as the technical term for the purpose of the translation. "The top-ranking rule ---- 'skopos rule', which means “that as a general rule it must be the intended purpose of the target text that determines translation methods and strategies”(Vermeer, 1978:100); that is, the end justifies the mean (Nord, 2001:124).

The second one is the Coherence Rule. The coherence rule emphasizes that the target text must be interpretable and consistent with the intended receiver's cultural background. In other words, the target text must be coherent and understandable for the target readers, taking their cultural background and knowledge into account first. As for the coherence rule, the source text is not the most authoritative material any more, instead, turns into only part of the translation works. It has to be translated into a target language in such a way that it becomes part of a world continuum which can be interpreted by the recipients as coherent with their situation (Vermeer, 1978:100)

The third one is the Fidelity Rule. It means translation is a preceding supplier of information and a translation work should be as faithful as possible to the original one. This is regarded as a further principle, later turns into the "fidelity rule" by Reiss and Vermeer in 1984. Besides, the fidelity rule is regarded as subordinate to the coherence rule, as well as the subordinate to the skopos rule. If the purpose requires an alternation of function, the adequacy or appropriateness with regard to the purpose will be given great priority, instead of the criterion of fidelity to the source text.

2.2 Domestication and Foreignization
Domesticating translation and Foreignizing translation was put forward by Lawrence Venuti in 1995. These technical terms come from an essay written by Germany scholar Schleiermacher in 1813. Schleiermacher emphasizes the indispensable relationship between translation and understanding and points out that translation can be generally divided into two forms, one is a translation that follows closely not only the content but also the form of the source language, the other is a translation catering to the target readers’ cultural background and knowledge in order to enable readers to comprehend exotic flavor.

Domestication refers to the target-culture-oriented translation strategy in which unusual expressions to the target culture are paraphrased and replaced by some familiar ones to the target readers so that they can comprehend translated text easily. Nida is a representative of those who are in favor of domestication. He puts the target readers at the first place from the perspective of society and culture and emphasizes from time to time that translated texts should be the most suitable equivalence to the source text. To receive the meaning of the source language, readers need not to accept the original culture. Take “to grow like mushrooms” as an example, in Chinese we can use “雨后春笋” to help us catch the original meaning instead of “像蘑菇一样生长”.

Domestication aims at delivering original meaning to readers more clearly and fluently. The essence of Domestication is to change or replace some terms, paraphrase specific background so that translated text can be understandable and elegant. Qian zhongshu, the great Chinese literary scholar and writer, is an advocator of domestication in translation. He translated “吃一堑长一智” into “A fall into a pit, a gain in your wit.” He tried his utmost to keep source language consistent with target language in terms of pronunciation, sentence structure and style so that intended readers could comprehend the beauty and vividness of original language. 归划或异化从翻译目的论角度看中国文化特有词语的英译(4):http://www.youerw.com/yingyu/lunwen_594.html