This book focuses on the analysis of discourse coherence in the English learning advertisements as a special multimodal genre.The choice of discourse coherence as the starting point to study this specific genre is based on the following considerations：

First of all，the English learning advertisements are complex multimodal discourses in which a large amount of semiotic elements，including verbal and visual，are organized in a hierarchical and embedded structure.The English learning advertisements incorporate characteristics of different genres，such as educational genre，promotional genre and scientific genre.This diversity and heterogeneity of semiotic means of expression and of composition make the construction of discourse coherence a fascinating research endeavor.

Secondly，discourse coherence and genre are deeply intertwined.Genre is a functional model of semiotic resources and social context.That is，genre mediates between discourse and social context.Therefore，since the discourse features are mediated through genre，the pattern of discourse coherence is also relativised to genre（Unger，2006）.Any analysis of discourse coherence has to be genre-based.Therefore，the current book takes the English learning advertisement genre as the basis to systematically describe and analyze the ways in which discourse coherence is constructed in multimodal discourses.

Thirdly，genre also contributes to the construction of discourse coherence.As Eggins and Martin（1997：235）argue，the coherence of texts rests only partially on textual cohesion，generic structure also contributes to the coherence of texts，and is claimed to be another facet of textual coherence.That is，genre，in the sense of generic structure of texts，is described as“a further significant device which enables each text to function as a semantic unit”（ibid：237）.According to their view，generic structure of the genre is also an important factor in the construction of discourse coherence.With this consideration，the current book includes an analysis of the generic structure of the English learning advertisements genre.More detailed discussion of genre's role in constructing discourse coherence will be performed under the facet of global coherence.