On Approximate Number Expression "X+(classifier)+Zuoyou(left And Right)/Shangxia(up And Down)"

Adding "Zuoyou(left and right)" or "Shangxia(up and down)" after the Numeral or numeral phrases is a common way to express approximate number in modern Chinese.For example:Wushi Zuoyou(about fifty)、Liushi sui Shangxia(about sixty years old).We term it as "X+(classifier)+Zuoyou(left and right)/Shangxia(up and down)" pattern.Inmost dictionaries,the explanation of the "Zuoyou(left and right)" and "Shangxia(up and down)"in the format is same in the usage and meaning.Through investigation and statistics,we found the two words were interchangeablein most cases.But in some cases,the"Zuoyou(left and right)" and "Shangxia(up and down)" in the format could not be exchanged,which illustrated that there were some differences in the description of approximate number.Nevertheless,most researches don’t illustrate clearly the similarities and differences.This made it easy for foreign students to become confused and make some errors in the course of using.First of all,we adopted the method of combining form and meaning to describe the"X+(classifier)+Zuoyou(left and right)/Shangxia(up and down)" format on syntax and semantics according to a large number of authentic corpus.And,combining the Theory of Fuzzy Linguistics,the fuzzy restriction effect of "Zuoyou(left and right)" and"Shangxia(up and down)" in the expression of sentences was described.Combining the Theory of Figure-Ground,the prominent effect of the "X+(classifier)+Zuoyou(left and right)/Shangxia(up and down)" format in the expression of sentences was illustrated.Through the description,we found that there were different differences between the two words on syntax,semantics and pragmatics.Therefore,we made a contrastive analysis between the two words on syntactic structure,syntactic function,semantic function,pragmatic function,frequency of use and style of writing.By comparison,we found that there was a big difference between the two words in terms of frequency of use and meaning type.Finally,we made a cognitive explanation of the causes of the differences.