Syntactic Complexity Of English Sub-clauses:A Study Based On Syntactic Treebank

English sub-clauses have syntactic complexity,which can be detected by mean dependency distance(MDD).At present,there are still not any studies about syntactic complexity of nominal clause and adverbial clause except relative clause in academic circles,which means that the related researches are not systematic and holistic.Based on dependency grammar,this study considers English sub-clause as research objective and the calculation of dependency distance as research method and 300 English complex sentences,including one hundred relative clauses,nominal clauses and adverbial clauses respectively selected from The New York Times from January to April,2016,as research data.We have used Excel 2013 to make the sentences annotated to establish treebank,employed quantitative research methods to calculate the MDD of all the sub-clauses and tested the significance of difference between MDD respectively by SPSS16.0.Based on the previous research findings,we have analyzed their syntactic complexity qualitatively.Finally,according to MDD,we have compared the syntactic complexity of the sub-clauses and created the continuum of syntactic complexity for the sub-clauses.There are three findings:(1)Adverbial clause has the higher syntactic complexity than nominal clause and relative clause,between which there is no significant difference.They have the following hierarchy relations: AC > NC = RC;(2)The hierarchy relations of subdivisions of the three types of sub-clauses in syntactic complexity are as follows: relative clause: SO = OO > SS;OO > OS;SO = OS,nominal clause: SC > OC = CA;SC = PC;PC = OC = CA;ESC = PC = OC = CA;OSC > ESC and adverbial clause: FAC > BAC;(3)Based on the continuum of all the sub-clauses in syntactic complexity,syntactic complexity of SS is lowest while that of FAC is highest.