Chapter Five concludes the thesis by restating the purpose and significance of the subject, sums up the achievement and defects of the thesis and provides direction for future research.

• 第五章是对本文的总结，重申了笔者从事本课题研究的主要目的和意义，对本文的研究成果和不足之处做了简单的归纳，提出了今后进一步的研究方向。