The authors point out in this thesis that modal verbs and auxiliaries are identical to each other in syntactical functions,therefore they should be taken as the same category.

• 对情态动词的句法特点进行了分析,并在这一分析的基础上提出了自己的看法,认为情态动词和助动词具有句法上的同一性,应该属于同一语类,这更符合句法普遍性和经济性的特点。