| Sentence is the basic unit of an article.The complexity of sentences determines the quality of an article and reflects the students’ language ability and level.The development of syntactic complexity is an important part of second language learners’ target language acquisition and development,which has always been regarded as an important construct in the field of second language teaching and researching.In second language teaching,although there are many standards for measuring the quality of an article,a good article must have a variety of sentence patterns.Therefore,L2 writing teaching must pay attention to the complexity of learners’ sentences in writing.Syntactic complexity is represented by the variation and complexity of output units or grammatical structures in second language writing.Researches on syntactic complexity at home and abroad both focus on investigating the relationship between the measurement indicators of syntactic complexity and second language writing.The research subjects are mainly undergraduate students or higher education learners.The sentence conversion training is to improve the syntactic complexity of students by training students in Chinese-English syntactic translation,multi-translation and so on.For sentence conversion training,the previous studies are only at the theoretical level,which provide research space for the following research.On the basis of previous studies,this research further demonstrates sentence conversion training.Through a15-week sentence conversion training on the experimental group,the research analyzes the syntactic complexity of high school students’ writing,aiming to investigate the following three questions:(1)What are the characteristics of syntactic complexity in high school students’ English writing?(2)What is the effect of sentence conversion training on syntactic complexity in high school students’ English writing?(3)Does sentence conversion training improve high school students’ understanding of syntactic complexity in writing effectively?This research selected 80 high school students’ English composition texts as samples from two classes of Grade One in Jinan.The data results were obtained by L2 Syntactic Complexity Analyzer(L2SCA)and SPSS.Through the analysis,the findings are as follows:(1)At length of production unit dimension,high school students have a tendency to write long sentences so as to improve their English writing level,however,the length of sentences is not the only criterion for determining the writing level.At sentence complexity ratio dimension,high school students’ sentence complexity ratio is low.At amount of subordination dimension,students have a tendency to write complex sentences regardless of whether they are in high-score group or low-score group.At amount of coordination dimension,the usage amount of coordination increases with the improvement of high school students’ writing levels.At amount of particular structure dimension,students with high writing proficiency use more complex nominal phrases than verb phrases.(2)Sentence conversion training can improve high school students’ syntactic complexity indicators.At the dimension of length of production unit and particular structures,the average value of the post-test in the experimental group is significantly higher than that of the pre-test in the experimental group.At the dimension of the sentence complexity ratio,subordination and coordination,the post-test data in the experimental group are slightly higher than the pre-test data.In summary,all indicators of 14 syntactic complexity increase in the experiment group,which reveal that the sentence conversion training has a favorable teaching influence on improving high school students’ syntactic complexity.(3)Sentence conversion training can improve high school students’ awareness of syntactic complexity.After comparing the results of the interview before and after,the research draws a conclusion that students have a clearer understanding of the syntactic complexity.Students can realize that the length of sentences is not the only criterion for determining the writing quality.The long sentence cannot represent that the sentence is complex.The quality of an article is also related to the coordinate phrases,complex nominals and so on.This study verifies that sentence conversion training has positive significance in improving students’ syntactic complexity.Sentence conversion training can effectively improve the syntactic complexity of high school students,which is also of certain reference significance for teachers in writing teaching. |