| The research work of this paper goes round the two typical selective compound sentences, which are "Yuqi A, Buru B" and "Yuqishuo A, Burushuo B". The guiding ideology is the theory of small triangle which was put forword by Xing Fuyi, a famous and respectful linguist in modern and contemporary China. Firstly, a comprehensive study will be made over the language form of "Yuqi A, Buru B" and "Yuqishuo A, Burushuo B". Then, it compares these two compound sencentences in its meaning and content, including subject, predicate, logical semantics, cognitive level. Finally, it examines the pragmatic value of these two compound sentences and tries to analysize the mentality characteristics in different contexts when it is used. The theory of small triangle is the soul of the paper, at the same time, we also learn from the practice of cognitive linguistics.There are four parts in this paper.In the first part, research status, research thoughts, research methods, data sources will be set forth.In the second part, it clearly examines the language form of "Yuqi A, Buru B" and "Yuqishuo A, Burushuo B" and Specifically analysizes their subject, predicate, subject and conjunction words and structure features. The subject part is divided into two aspects, the first aspect is whether the subjects of before clause and after clause can appear at the same time when the subjects in them are same and different. The second aspect is what kind of words can serve as the composition of the subject. The predicate part includes the rules of core verbs and the requirements of the component which modify the core verbs. The part of conjunction words is described with two sections which are the omission and replacement of conjunction words and the location problems of the subject and conjunction words. The structure characteristics are analyzed from two aspects, firstly, the paper explores their combination rules, including comparable structure and incomparable structure. Secondly, we study their aggregation rules, namely, their function in larger syntactic component when these two sentences serve as a small syntactic component.The third part is the study of the meaning and content of "Yuqi A, Buru B" and "Yuqishuo A, Burushuo B". To the beginning, it explores the meaning and content of their subjects, including the semantic components of subject and the meaning and content of subject. and then the predicate language meaning will be discussed into two portions which are the rules ofthe predicate and the semantic relationship of subject and predicate. Furthermore, it explores the conditions of additions and substitutions of the conjunction words. Finally, the paper focuses on the semantic relationship of "Yuqi A, Buru B" and "Yuqishuo A, Burushuo B", including the basic semantic relations, semantic classification and logic semantic relations of before clause and after clause.The fourth part is to discuss the pragmatic value of "Yuqi A, Buru B" and "Yuqishuo A, Burushuo B". In this part, we discuss their mentality characteristics in different contexts when people use these two sentences of "Yuqi A, Buru B" and "Yuqishuo A, Burushuo B", trying to reveal the abundant and rich pragmatic value of two sentences.The fifth part is a summary of this paper. Specifically, it tries to draw a terminal conclusion as simple as we can and to reveal the true distinction between "Yuqi A, Buru B" and "Yuqishuo A, Burushuo B" from the three aspects of language form, language meaning and pragmatic value. |