3.1　The Idea of Corpus Building

Corpora can be divided into several types according to different criteria.According to the representativeness and purpose of study，it can be divided into general corpora and specialized corpora.Considering the variety and organization of language，it can be divided into monolingual corpora，bilingual corpora and multilingual corpora.On the basis of the aging of language，corpora can be divided into synchronic corpora and diachronic corpora.In consideration of the format of language，corpora can be divided into w ritten corpora，spoken corpora and video corpora.(https://www.daowen.com)

The corpus compiled for the book is a specialized，comparable，synchronic，w ritten and full-text one.The steps of corpus building will be introduced in the following.