The main conclusions of this article are the following : Firstly the syntactic structure of comparative sentences is very flexible though semantically it must have three components : comparative item ( including comparative subject and comparative object ) comparative result and comparative marker .

第一，不及范畴比较句 句法形式灵活多变，但其语义要求此类句式的构件必须包括比较 项（包括比较主体和比较客体），比较结果和比较标记。

The Comparative Construction is a special sentence structure in contemporary Chinese whose syntactic meaning mainly reflected by the conclusion item .

差比句是现代汉语中的一种特殊句式，它的 句式意义主要体现在结论 项中。

According to these two theories only in certain syntactic structures can a lexical item be semantically and grammatically right in a phrase clause or sentence .

这两个理论认为，当使用于短语、从句或句子中时，词 项只有在特定的 句法结构中才能语义正确、合乎语法。

Moreover there is no syntactic item of directional complement in many other languages . Therefore the directional complement is also difficulty .

另外，在很多语言中都没有趋向补语这一 语法 项目，以致趋向补语成为留学生学习的难点之一。

' BE ' is widely used in English and is related with many other syntactic rules and therefore the use of ' BE ' is a very important item in grammar acquisition .

BE在英语中应用广泛，涉及众多 语法规则，因而有关BE的使用是英语中一个很重要的语法习得 项目。