复习资料（4.5）
5、The linear word order of a sentence 句子的线性词序
When a sentence is uttered or written down, the words of the sentence are produced one after another in a sequence. Meanwhile, they are heard or read as arranged one after another in a sequence. This sequential order of words in a sentence suggests that the structure of a sentence is linear.
我们说出或写下一个句子，其中的词语是按次序一个接一个出现的。同时，对方也是一个接一个次序听到这个词语的。句子中词语的这种有次序的排列表明，句子的结构是线性的。
6、The hierarchical structure of a sentence 句子的层次结构
The superficial arrangement of words in a linear sequence does not entail that sentences are simply linearly structured. Sentence structure is hierarchical in nature.
组成句子的单词表面上的线性排列并不意味着句子仅仅是线性结构的。句子实际上是有层次结构的。