单句层面的各同义句式看似语义相同,然而若从更广阔的语篇视角看,在进入上下文时,同义句式存在选用上的差异,其进入语篇并非任意的,而是受到了诸多因素的制约,包括话题性、信息原则、语域等。在具体的语篇中,存在着“优选”句式。这种分析主要是基于系统功能、话语分析理论而得出的。本研究对汉语作为第二语言的教学(TCSL)具有应用价值。 Synonymous sentences at the sentence level seem to have the same semantic meanings. However, when viewed from a broader discourse perspective, there are differences in the choice of the synonymous sentences when entering the context. The entering texts are not arbitrary but are subject to Constraints of many factors, including topics, the principle of information, register and so on. In the specific discourse, there is a “preferred” sentence. This analysis is based on the system function, discourse analysis theory. This research has the application value to Chinese as the second language teaching (TCSL).