2．1 Conversion of Word Classes词类转译
First of all，we should know what word classes are．In English，word classes are sometimes called parts of speech traditionally．There are 2 major kinds of word classes: open classes and closed classes．Nouns，verbs，adjectives and adverbs are known as open classes because their membership is fairly open-ended，in the sense that we can readily coin new words to add to them．The closed classes，however，have a fairly fixed membership．They are pronouns，prepositions，conjunctions，auxiliaries．Numerals and interjections are marginal classes．Conversion，one of the commonly adopted translation techniques，means the change of word classes in translation．Owing to the syntactical differences between English and Chinese，it is usually impossible for the translator to keep to the original word class in the process of translation．As a matter of fact，a word belonging to a certain word class in English language sometimes has to be converted into a different word class，so as to bring forth a readable and coherent sentence．In conversion from English into Chinese，there are following cases for us to consider while translating．