ξ1句首位置语法学者在分析句子时经常会使用这三个术语：句首，句中，句末。人们发现，居于这三个不同位置上的语言成分的性质有很大的区别。但如果进一步深究的话，至少句首这个位置是不太明确的。这就是说，和句首位置相关的语言成分的性质也很难说是明确的。这在汉语语法研 ξ1 Sentence position grammar scholars often use these three terms in the analysis of sentences: Sentence, Sentence, Sentence. People find that there is a big difference in the nature of the language components in these three different places. However, if you look further, at least the first sentence of this position is not clear. That is to say, the nature of the language component that is related to the position of the sentence is hard to say. This is the study of Chinese grammar