复习资料（4.12）
15、D-structure and S-structure深层结构和表层结构
What syntactic movement suggests for the study of the grammar is that a sentence structure may have two levels of syntactic representation, one that exists before movement takes place, and the other that occurs after movement takes place. In formal linguistic exploration, these two syntactic representations are commonly termed as D-structure (the deep structure) and S-structure (the surface structure). It is believed that phrase structure rules, with the insertion of the lexicon, generate sentences at the level of D-structure, while the application of syntactic movement rules transforms a sentence from the level of D-structure to that of S-structure.
句法位移对语法研究的启示是，一个句子结构可以有两个层次的句法表现，一个存在于位移发生之前，一个存在于位移发生之后。在正规的语言学研究中，这两种句法表现称为深层结构和表层结构。短语结构规则通过插入词汇在深层结构上生成句子，而应用句法位移规则又把句子从深层结构转化到表层结构。
Since syntactic movement does not occur to all sentences, the D-structure and S-structure of some sentences look exactly the same at different levels of representation.
由于并非所有句子都能发生句法位移，因而一个句子的深层结构和表层结构在不同的表现层次上是完全相同的。