本文提出了“语义块”这一句子语义结构的分析单位 ,并借助它来研究句法同义转换的机制。我们发现 ,句法同义句具有相同的语义块构成能力 ,但是语义块的认知显著性有所不同 ,从而导致了语义信息内容相同的句子具有不同的表层句法结构。 This paper proposes the unit of analysis of the semantic structure of the “semantic block” and uses it to study the mechanism of syntactic synonymous transformation. We find that the syntactic synonymous sentences have the same ability of constructing semantic blocks, but the cognitive significance of the semantic blocks is different, which leads to different surface syntactic structures of sentences with the same semantic information content.